Controlling Aphids in Early Spring

 

Young eggplant struggling against lots of aphids.
Photo Pam Dawling

Controlling Aphids in Early Spring

Aphids can get out of control in early spring as they become active before their native predators, such as ladybugs, emerge from hibernation. We have a particular problem in our hoophouse and in our greenhouse on the eggplant, pepper and tomato transplants from mid-April to mid- to late-May depending when we manage to get them under control.We’re planning now, so we can be ready next spring.

There are many kinds of aphids. The lifecycle of aphids starts in spring with eggs hatching into wingless females that give birth via parthenogenesis to more females. Within a week, one female can produce 100 clones, which can repeat the process at the age of one week.  This continues until adverse weather or predators trigger production of a generation of winged female aphids that moves to new plants. Later in summer male aphids are born and females lay fertilized eggs that overwinter on host plants, to hatch the following spring.

Climate change is making the problem worse: for every 1degree Celsius rise in average temperature (about 2 F degrees), aphids become active two weeks earlier.

Newly planted insectary circle of flowers to attract beneficial insects.
Photo Pam Dawling

Organic Integrated Pest Management

I have a blog post about our organic integrated pest management, a step-by-step method of pest management which starts with actions least harmful to the ecosystem, only employing biological controls such as botanical sprays and selective pesticides if necessary after all other steps have been insufficient.

I recommend the ATTRA online publication Organic Integrated Pest Management. Each of the 22 pages is a poster, complete with good photos and concise clear info. Extension.org has an article on Organic Integrated Pest Management that explains how to  tackle pest problems one step at a time with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops.

Steps in Organic Integrated Pest Management:

  1. Prevent infestation: Cultivate a good environment for your crops: healthy soil, sufficient space, nutrients and water, suitable temperature, soil pH. Practice crop rotation to reduce the chances of pests and diseases carrying over from one crop to the next. Clear old crops promptly, so they don’t act as a breeding ground for the pest. Choose suitable varieties that resist the pests you most expect.
  2. Cover or protect the plants physically from the pests (mulches to stop soil-dwelling pests moving up into your crops, netting, rowcover, planting diverse crops, and even growing trap crops)
  3. Provide habitat for natural enemies and other beneficial insects
  4. Monitor crops regularly at least once a week and identify any pests you see.
  5. Introduce natural enemies of the pest (bacteria, fungi, insect predators or parasites)
  6. Hand pick and kill the pests if the pest population is above the action threshold. Many fruit and root crop plants can take 30% defoliation before any loss of yield. Where the crop is the foliage, this may be too much!
  7. Use biological controls (often derived from natural enemies) if the damage is still economically significant after trying the earlier steps in the process.
A pepper leaf with tiny aphids.
Photo Pam Dawling

 Applying these principles to dealing with early spring aphids

1.      Prevent infestation If you act before the aphids arrive, you can use a fine mesh netting to keep them off your plants, but monitor to make sure no aphids have got inside the net. Control ants (which farm aphids for their sweet excretions). Reputed repellents that I have not tried: dilute garlic, onion or chilies with water; diatomaceous earth (health hazard from inhaling gritty particles); vegetable oils.

2.      Cover or protect physically. You could try trap crops of nasturtiums to draw aphids away from your crop, but how much of your space do you want to devote to nasturtiums, and how do you deal with them then? The same choices as on food crops.

3.      Provide habitat for natural enemies. Plant for a continuous supply of insect-attracting blooms, that flower early in the year and attract aphid predators such as ladybugs, lacewings, syrphid flies (hoverflies), damsel bugs, big-eyed bugs, and spiders. Grow some early blooming flowers with pollen and nectar they can use as alternative foods. Sow seed in fall for earliest bloom.

Native annuals are some of the earliest bloomers that attract beneficial insects:

Tidy Tips (Layia platyglossa), a spring flowering wild annual in the aster (sunflower) family. The white tipped yellow daisy like flowers are 2” (5 cm) across. A native of California, it grows up to 2ft (60 cm) tall. The seeds attract birds. Flowers have special value to native bees. Tolerates cold to -5°F (-20°C). Likes full sun. Seed is widely available. To start indoors, sow seeds 6 to 8 weeks prior to planting outside. Do not cover; seeds need light to germinate. Seeds germinate in 8-12 days at 65-70° F (18-21°C). Temperatures above 70°F (21°C) inhibit germination.

Information from Laura Blodgett in the Daily Improvisations blog, Southwest Idaho: Starting Tidy Tips from seed in February was too early. The seeds sprouted within a few days. The plants were sturdy from the start. It was too cold to plant them out, but they had so much growth that they were cramped in their small pots. There were enough warm days in March to harden them off, even though temperatures got down in the mid 30’s F (1-3°C) a few nights.

Meadowfoam (Limnanthes douglasii) commonly known as poached egg plant and Douglas’ meadowfoam. The five-petalled 1” (2.5 cm) flowers have yellow centers and white edges. A fast-growing bushy annual, very attractive to hoverflies, butterflies and bees. Requires insect pollination. It grows 6-12” (15-30 cm) tall and wide. Hardy to zone 2. Germinate below 60°F (16°C) (in fall?). May need light for germination. Easy to transplant, but don’t let it dry out! If spring-sown, may not flower until early summer (too late for aphid control). Temperatures below 55°F (13°C) will hinder flower opening as well as honey bee flight.

Baby blue eyes (Nemophila menziesii) is a low spreading, shrub-like plant with succulent stems and flowers with six curved blue petals. It grows 6-12” (15-31 cm.) high and wide. You can expect baby blue eyes flowers in late winter where temperatures are moderate and the plant blooms until late spring to early summer. Wait until soils warm to nearly 60°F (16°C) to sow seeds. Sow shallowly, about 1/16 inch (2 mm) deep. Baby blue eyes flower will germinate in 7-10 days with cool weather and short days. Baby blue eyes self-seeds readily but does not transplant easily. Butterflies, bees, and other helpful insects use the nectar as food. Pinch the tips of the growth to force bushier plant formation. Once the plant has flowered and seed heads formed, cut them off and dry them in a paper bag. Shake the bag after a week and then pick out the larger pieces of chaff. Transplant carefully 6-8 weeks after sowing. Sow in the fall, (but not frost-hardy? winter hardy in zone 7 and warmer?) then blooms from early spring to mid-summer. Baby blue eyes will die out if too hot in summer. Water frequently, provide shade (without hindering insects!)

Borage attracts many beneficial insects.
Photo Raddysh Acorn

Other annuals:

Borage is a warm-season annual, fast at producing nectar, taking about 8 weeks to flower from sowing. Borage grows 1-3 feet (30-90 cm) tall and wide; it blooms from early summer until the first frost in fall. Borage can be started indoors 6-8 weeks before the last frost. Seeds germinate in 7-10 days. Transplant borage seedlings outdoors after the last spring frost. Be careful when transplanting not to damage the taproot. Seeds can also be sown in the fall and will germinate the following spring.

Sweet Alyssum is a great insectary plant for aphid predators.
Photo Raddysh Acorn

Alyssum is a small plant we have used in broccoli and cabbage beds to attract beneficial insects. Sweet alyssum attracts three main groups of predatory beneficial insects a) Minute pirate bugs (they eat aphids, thrips, mites, psyllids, and insect eggs), b) Parasitic wasps (they lay eggs in aphids, beetles, flies, moths, sawflies, mealy bugs, and scales. The larvae hatch and eat their way out, killing the host. c) Hover flies, aka syrphid flies (the larvae feed on aphids). Alyssum flowers also attract butterflies and bees. Buy Sweet Alyssum, not the ornamental cultivars.

Shungiku, Chrysanthemum Greens, Chopsuey Greens, Glebionis Coronaria, is in the aster family, Asteraceae. It is native to the Mediterranean and East Asia. The plant’s greens are used in many Asian cuisines.  Shungiku is easy to grow and the leaves, young shoots and stems can be eaten. Leaves are aromatic, with a strong flavor. Some describe the taste as between celery and carrots. Even the petals and seeds can be eaten. Small House Farm grows this (and sells seed). Bevin says it does attract bees, butterflies and predatory insects. It would probably do well in the winter hoophouse, and could be provoked into bolting early in the spring.

Shungiku chrysanthemum greens.
Photo Small House Farm

Biennials:

Dill is a biennial umbellifera, often grown as an annual. It is easy to grow, germinating in 10-14 days. It doesn’t transplant easily (although we do it every year without a problem). It does self-seed readily, so to prevent this, cut the seed heads before the seeds turn tan. The leggy plant grows 2-4 ft tall (60-120 cm) and half as wide. Each plant grows only one hollow stem with an umbrella-shaped flower head from mid-summer to fall (too late for spring aphid predators). Dill tolerates cold and heat, but will likely die back to the ground after the first hard freeze. It might not be the easiest to include in a hoophouse.

Angelica is a biennial that can flower in the spring of its second year.

Perennials:

Phacelia.
Photo Territorial Seeds

Phacelia is a particularly useful perennial plant in early spring if it has overwintered as it is an early pollen source for bees coming out of hibernation. Sow in the fall for early spring blooms – Phacelia will survive mild frosts to bloom in spring. It winter-kills at approximately 18˚F (-8˚C). The seeds need darkness to germinate, and then the plants like to grow in full sun. Phacelia flowers from 6-8 weeks from spring sowing for a period of 6-8 weeks with lavender blooms that attract syrphid flies, bumblebees, honeybees and native bees, and also aphid predators like hoverflies and parasitic wasps. It can grow 6-40” (8-100 cm) tall, given the chance.

Yarrow is a perennial, hardy to zone 5. Common Yarrow (with flowers that range from white to red) is hardy down to zone 3. It attracts an array of beneficial insects. In addition, the scent of yarrow repels deer and mosquitoes.

Fennel, Foeniculum vulgare (common fennel), is an herbaceous perennial commonly grown as a summer annual. 5-7 ft (1.5-2 m) tall; each stem branches near the top and each branch ends with a flat-topped cluster of small yellow flowers; fennel looks very much like dill but is taller and coarser. Fennel blooms from mid-summer to frost. Too late and too tall for our goal of attracting spring aphid predators in the hoophouse.

Coyote bush, (Baccharis pilularis), also called chaparral broom, is a native shrub related to sunflowers. It may be a low-growing shrub or an erect tall bush, depending upon its growing conditions, and so may not be a good candidate for a potted plant in the hoophouse! It attracts syrphid flies, as well as bees and butterflies, with its abundant winter bloom.

Dandelions. If you decide to trust to weeds to feed your beneficial insects, take care about how much seed they sow!

4.      Monitor crops at least once a week

5.      Introduce natural enemies: We do have an aphid parasite in the hoophouse as we do find mummies, but not enough to control an aphid outbreak in spring. Parasitic wasps for aphids include

Aphidus colemani eggs hatch into larvae which feed on the nymphs from the inside, the nymph swells and hardens into a leathery, grey or brown colored mummy similarly to effects of Aphelinus abdominalis. Once larvae mature, adult A. colemani wasps chew their way out of the aphid mummy and emerge to seek out aphids. These parasites are a good choice for year-round use (in greenhouses and outdoors) as the short days of winter do not affect them. Optimum Conditions: 70-77°F (21-25°C), 80% relative humidity. Release rates: 500-3,000 per acre, 2-3 times at one week intervals, depending on the extent of infestation. This product controls aphids, especially melon and cotton aphids Aphis gossypii, but also attack green peach aphid Myzus persicae, tobacco aphid Myzus nicotianae and bird cherry-oat aphids Rhopalosiphum padi. Price $243 for three batches of 500, including overnight shipping, from Arbico Organics.

Aphidus ervi will consume all types of larger aphids, especially the potato aphid, Macrosiphum euphorbiae, and the glasshouse potato aphid, Aulacorthum solani. It also parasitizes Myzus persicae var. nicotianae, as well as aphids such as Sitobion sp., Schizaphis sp., Rhodobium sp., Acyrthosiphon pisum and others. Use Aphidius ervi especially when aphid infestations are just beginning, as control will be easier to achieve before the aphid population’s explosion. Aphidius ervi are shipped in a 125 ml bottle that contains at least 250 mummies and adult aphid parasites. The bottle has a ventilated cap for optimum humidity. A sugar-water feeder ring ensures adult survival. Release the emerged adults within 18 hours of receipt.  The parasitized aphid swells and hardens into a leathery, grey or brown colored mummy. The first mummies can be seen in the crop approximately 2 weeks after the first introduction. Use at the rate of 1 adult per 20-100 sq ft (1 per 2-9 m2) for preventative use. 250 mummies is sufficient for 5000-25,000 sq ft (460-2300 m2). Dose rate may be increased 5-fold for hot spots. Introduce A. ervi weekly for at least 3 weeks. Cost from Arbico is $101 including shipping each time, $303 likely. Monitor weekly and make further introductions as required. When pruning leaves, check for parasitized aphids (brown mummies) and if present, keep these leaves in the greenhouse until new parasites emerge. Because they fly as soon as they emerge, you need to cover doors and windows with mesh screens.

Another option is a predatory gall-midge, Aphidoletes aphidomyza, the larvae of which hunt and kill aphids. Kills over 60 species of aphids, especially those in greenhouses and hoophouses, including green peach aphid Myzus persicae; and  the hemlock woolly adelgid Adelges tsuga. Optimum conditions: 64-77°F (17-25°C) with RH of 70%. Shipped as pupae. The adults hatch within 1-12 days. After hatching, females lay eggs among aphid colonies. The eggs develop into larvae, and seek out adult aphids, injecting a toxin in their legs to paralyze them. Then they bite a hole in their thorax and suck out the body contents. Use 1 predator per 10 sq ft (1 m2), 2-3 predators per 10 sq ft (1 m2) for heavier infestations or 4,500 per acre (0.4 hectare) weekly until infestation subsides. 1000 for a 96x30ft (29×9 m) hoophouse, cost $125 including shipping per week, perhaps $375 total.

Lifecycle of the Green Lacewing
Photo J.K. Clark

Green Lacewing adults feed on nectar, pollen, and aphid honeydew, and the larvae are active predators of soft-bodied insect pests: aphids, thrips, whitefly, leafhoppers, spider mites (especially red mites) and mealybugs. After hatching, green lacewing larvae seek out prey – pest eggs, nymphs or adults. They feed for 2-3 weeks, spin a cocoon, and emerge as adults 10-14 days later. Lacewings have the ability to tolerate wide temperature ranges and work well with most other beneficial insects. Green Lacewing Eggs: Best low-cost biological control for common garden pests. If you want to establish Green Lacewings at the beginning of the season or have a limited infestation, choose the appropriate numbers of eggs for your garden or greenhouse. It takes 3-10 days for larvae to emerge depending on the temperature and other environmental conditions. Repeat applications every 1-2 weeks. Green lacewing eggs are available in loose media or on hanging cards for easy release. Green Lacewing Larvae: Best for immediate treatment of a pest problem. If you have a more severe infestation, buy the larval frames or bottles, which provide the quickest means to control unwanted pests – the larvae arrive ready to feed. Adult Green Lacewings: Best for establishing a population. If you are treating a large area and want to create a stable population, buy adult lacewings. The adults come ready to lay eggs throughout the release area. They do not actively control pests themselves. Cost 1000 eggs on cards $30 each time; 1000 larvae $61 each time; 100 adults $85. All prices include shipping.

A ladybug on the leaf stem of a sunflower planted to attract beneficials.
Photo Pam Dawling

Ladybugs. live ladybugs are best used when pest numbers are low, but can be used to fight existing infestations. Ladybugs primarily feed on aphids, but will prey on a variety of other pests including mealybugs, thrips, soft scale, whiteflies and spider mites. Each adult can consume up to 5,000 aphids in a lifetime. The larvae eat 50-60 aphids per day. Optimum Temperatures: 62-88°F (15-31°C). Ladybugs are prone to flying away. Help keep them around and attract native species by planting perennial and annual flowering plants and by avoiding chemical sprays. Create shaded areas or plants with dense canopies to provide alternative habitat when conditions are not ideal. While these methods may not keep all the ladybugs on site, they should help. If you have had issues with ladybug flight, consider using Assassin Bugs or Green Lacewing instead. 4,500 for up to 2,500 sq ft (232 m2). Cost $20/1500 plus Overnight or 2nd Day Air shipping.

6.      Hand pick and kill the pests if the pest population is above the action threshold. Handpicking aphids is likely impossible, so blast them off the plants with a water jet from a hose. This may decrease the population enough for natural predators to begin control.

7.      Use biological controls. Failing success with the methods above, a soap spray can be effective, although aphid predators will also be harmed. We use 3 Tablespoons (15 ml) per gallon (3.8 l) of biodegradable Murphy’s Oil Soap, in a sequence of 3 sprayings 5 days apart. The soap needs to hit the aphids to kill them. Soak both sides of the leaves and directly spray any visible pests. Murphy’s Oil Soap is made from lye (potassium hydroxide) or sodium hydroxide, and vegetable oils with 2% of synthetic ingredients including trisodium MGDA, Lauramidopropyl dimethylamine oxide (a non-toxic purifying agent), sodium tallate. Official insecticidal soaps are made from potassium salts of fatty acids (potassium laurate).

Insecticidal soap works in several ways. The soap penetrates insects’ cuticles, which causes their cells to collapse and dry out. Soaps suffocate insects such as scale insects. Soap sprays are also somewhat effective against chiggers, earwigs, fleas, mites, scales, and thrips. They are not effective on chewing insects such as caterpillars and beetles.

You can make your own soap spray if you have some fragrance-free liquid soap. You do not need to include oil. Note that “dish soap” is actually detergent, not a soap at all, so don’t use that. Test your homemade spray on a small part of a plant first and wait 24 hours to see if there is any damage. Look for spotting, wrinkling, or browning of leaves. If you see any trouble, don’t use the spray.

Soap sprays can be potentially damaging to some plants. Crops that are susceptible to damage from soap sprays include cucumbers, squash, melons, beans, and peas.

Neem is a botanical insecticide effective against aphids.

Best Options for our Hoophouse in April and May

Looking at the options for dealing with aphids and choosing those most compatible with pot-grown plants to flower in spring in our greenhouse and hoophouse, these seem our best chances:

  • ·         Cultivate a good environment for our crops.
  • ·         Monitor crops regularly once a week.
  • ·         Grow Meadowfoam from seed in the hoophouse in late October. Hardy to zone 2. Try February too.
  • ·         Grow Tidy Tips from seed in the greenhouse in February, pot up and move into the hoophouse just before flowering. Try starting some in late October too. Tolerates cold to -5°F
  • Grow Sweet Alyssum from seed started in February.
  • Grow borage form seed started in February. Move pots to hoophouse after April 1.
  • Grow perennial phacelia started in October and February for future years. Phacelia will survive mild frosts to bloom in spring. Protect from worse than “mild frosts”.
  • Grow yarrow from seed started in October and February. It is hardy down to zone 3.
  • Grow Shungiku from seed sown in late September, and provoked into bolting early in spring.
  • If we want to spend $100+ to deal with a bad infestation, buy 3 units of ladybugs.

Book Review: Sally Morgan, The Healthy Vegetable Garden

The Healthy Vegetable Garden
Photo Chelsea Green

Book Review: Sally Morgan, The Healthy Vegetable Garden: A natural, chemical-free approach to soil, biodiversity and managing pests and diseases.

Chelsea Green Publishing, September 2021

Sally Morgan is an expert organic gardener in the UK. She is the editor of Organic Farming Magazine for the Soil Association, the nation’s foremost non-profit organic gardening and farming membership organization. Her book The Healthy Vegetable Garden is clearly and concisely written. Sally promotes building healthy soil, boosting biodiversity, creating habitats to attract pollinators and predators, making good use of water, promoting the stability and resilience of natural ecosystems, and integrating the landscape with people.

A healthy garden maintains a balance where pest organisms are at a non-damaging level, (rather than eliminated entirely). Here you will find lots of solid information to identify pests and diseases and deal with them using regenerative principles, and when necessary, making traps and lures.

The book has some info particularly for US gardeners – you’ll be able to read about Mexican bean beetle and Colorado potato beetle! You might be mystified by some of the European details we don’t have to deal with, such as raspberry beetle or flatworms. As long as you have some prior gardening experience where you live now, you can only benefit from the information offered here. Brand new US gardeners might get confused.

The Healthy Vegetable Garden has good descriptions of soil and its components, structure, assessment, and testing. It is important to nurture healthy soils producing healthy plants, with the essential minerals and vitamins we need for health. Nutrient density has declined seriously over the last 70 years, particularly levels of calcium, iron and vitamins B and C. In 2014, the UN warned that we had only 60 years of harvests left, if we continued degrading our soils. In 2020 a new study estimated that 90% of soils had only 100 years of harvests left. Soils managed with conservation techniques have much longer projected lifespans.

The second chapter is about ways to regenerate soils, by minimizing tilling or digging, adding compost, mulches and cover crops. The living mulch section is where I am hesitant. My experience and that of Jesse Frost whose Living Soil Handbook I reviewed recently, is that living mulches can out-compete the crop if we are not skilled and careful. The author does point out the need to cut back the mulch to prevent this problem. Growers in the south might find planting zucchini (courgettes) into white clover impractical as zucchini is a fast-turnaround crop for us, whereas clover is a slow-growing cover crop. The author leaves the clover growing through the following winter, to make the combo work. In the chillier parts of the UK, only one crop of zucchini can be grown in a summer, so the system makes sense. In Virginia, we plant zucchini and summer squash 5 times outdoors. Likewise, the speed with which chickweed flowers and sets seed in Virginia would make it unwise to regard it as a cover crop! I did like the idea of undersowing tomatoes with coriander, if I wanted large volumes of coriander (cilantro).

Chickweed flowers.
http://ipm.ucanr.edu/PMG/S/W-CP-SMED-FL.006.html
Photo by Jack Kelly Clark.

The chapter on understanding pests and diseases is well-written, although we in the US have so many more than in the UK! Plant pests are listed in categories by their method of causing harm, rather than by individual names, which helps understanding. Plant pathogens likewise are described by type, as bacteria, viruses, fungi, water-molds. Fungal pathogens include biotrophs (parasitic pathogens such as downy mildews, rusts and smuts), semi-biotrophs that spend part of their lifecycle on the host, then part feeding saprophytically on the host’s dead remains (such as apple scab, Phytophthora blights, Botrytis-type molds and powdery mildews) and necrotrophs that kill their host and then feed as saprophytes. I appreciated the bigger understanding this classification of pathogenic fungi gave me.

Heed the warning that climate change is bringing new pests and diseases, and the chilling news that for every 1 Celsius degree rise in average temperature (about 2 F degrees), aphids become active two weeks earlier. Some warm climate diseases will move further towards the poles. The author recommends paying attention, encouraging good airflow around plants, sanitizing pruning tools, and planting rows of tall plants to break up the progress of air-borne fungal spores.  Growing potatoes downwind of a row of Jerusalem artichokes is a good example.

Sally is very practical on the subject of sterilizing pots and flats – your tools, boots, gloves and hands are as likely to spread spores, don’t worry about sterilizing pots! Some of the disinfectants suggested in other books can do more damage! Likewise, most spores don’t survive long on the ground, removed from their host plants, and so such diseased crops can be safely composted in a hot compost process. Practice crop rotation to deplete those that do survive in the soil, such as carrot rust flies.

Under normal conditions, predators can prevent pest outbreaks, but problems arise when conditions change quickly and disrupt the balance of prey and predator. If you see lots of pests, find a way to deal with them that won’t also kill their predators and parasites. Beware broad spectrum pesticides and fungicides, even if Organic. Encourage ladybugs and beetles by creating “ladybug hotels” and “beetle banks”. (There are some photos to inspire you.)

Plant for a continuous supply of insect-attracting blooms. Yarrow, ajuga, alyssum, dill, and fennel flower early in the year and attract predators like hoverflies, ladybugs, lacewings, tachinid flies, and parasitic wasps. Also grow early blooming flowers with pollen and nectar predators can use as alternative foods – borage is fast at producing nectar, as are dandelions. Phacelia is a very attractive to predators, especially aphid predators like hoverflies and parasitic wasps. Sow in the fall for early spring blooms. Angelica is a biennial that can flower in the spring of its second year. If you decide to trust to weeds to feed your beneficial insects, take care about how much seed they sow! This is a risk I do not recommend taking, especially in warm climates with rapid rates of growth.

Borage in an insectary circle.
Photo by Bridget Aleshire.

In the section on crop rotations, polyculture and continuous cropping, Sally reports that she has moved away from a rigid crop rotation for many crops, following Elaine Ingham’s observation that nature does not rotate. This may be a place where home gardeners and production gardeners diverge. Mixed beds with several crops work well for manual work, but less so for those with rototillers, or even those hoping to make fast progress with a scuffle hoe. Mixed plantings are attractive and fun for the solo gardener, but having others pull up your delightful medley suggests it doesn’t work so well for bigger operations.

This book is not dogmatic. Rotations help disrupt pest and disease cycles, and here you can read brief descriptions of three-crop, four-crop and eight-crop rotations. You can also devise ad-hoc rotations and grow beds of different crops next to each other, in order to benefit from diversity without slowing down your hoeing or putting a bed out of commission while you wait for the last item in that bed to finish its lifecycle.

Shumei Natural Agriculture Farm, Yatesbury, Calne, in SW England has been increasing yields year by year, with no rotation, no pesticides, and no fertilizers other than material from immediately around the beds that is incorporated into the soil. You can’t successfully switch instantly to this method of growing, because it takes time and lots of the right microbes for the soil to adapt. Charles Dowding is experimenting with this at Homeacres, his garden in Somerset. Continuous cropping is a challenging idea to those of us who came up when organics was the opposite of industrial monocropping. We championed rotations.

The author provides a list of perennial vegetables she is growing: Chinese artichokes, Jerusalem artichokes, globe artichokes, Good king henry, lovage, perennial kales, scorzonera, sea beet, sea kale, skirret, Babington leeks, potato onions, walking onions, and Welsh onions. No rotation is used for these no-dig crops, which grow with a layer of leaf litter on the soil.

Sally Morgan

Agroforestry is the practice of growing vegetables in wide alleys between trees. Sally has tried this by planting a row of cordon apples (trees trained to a single stem) along the edge of a vegetable bed. US readers should not follow her exact hedge design plan, as autumn olive, blackthorn and dog rose, for example, are invasive here.

Part 4 of the book is on boosting defenses, and how biocontrol works. This is the use of one organism to control a pest or disease. It is important to learn about the pests you have and their particular biocontrols. It’s not a case of opening the bag and throwing the stuff on!  Biocontrols have specific requirements, such as temperature or moisture. Timing is important.

Parasitic wasps, minute pirate bugs and predatory mites like Phystoseilus persimilis (which eats spider mites) can be introduced for their appropriate prey. Try to save biocontrols for when you really have a problem, and make sure you correctly identify the pest you want to control.

Predatory nematodes each have their own mutualistic bacteria living in their gut. When the predatory nematode works its way into its prey, it releases its bacteria, which kill and digest the prey. Reminds me of the Trojan Horse! The process happens below ground – nothing to see here! I found this fascinating! Nematodes need a film of water to live and move in, and temperatures above 41˚F (5˚C). Buy the right nematodes (and bacteria) for each job. This book has a two-page spread on which parasitic nematode to use for which pest. I have not seen this quality of information in any other book! Nematodes can be used to manage slugs, weevils, carrot rust fly, cutworms, onion fly, gooseberry sawfly, thrips, codling moth and more.

Plants have their own protective species. The introduction to the rhizosphere (microbiome around the roots) includes fascinating details on a type of morel mushroom that farms bacteria! Soil fungi are important for most crops, except brassicas and chenopods (beets, spinach and chard). We hear about the rhizosphere, but not the phyllosphere, the equivalent collection of micro-organisms on the leaves. This is mainly, but not only, composed of bacteria. About 10 billion on one leaf, and all different from the bacteria in the soil, and varying from one crop to another! Young leaves have mostly bacteria, mature leaves have more yeasts and senescent leaves mostly filamentous fungi. These microbes protect the plant’s health, supply biofertilizers, biostimulants and biopesticides. Some leaf bacteria suppress growth in caterpillars feeding on the leaf. Understanding this helps us appreciate the reasons for not spraying plants haphazardly with things that “might help”.

Plants have an arsenal of defenses. Thorns and hairs are just the most obvious. Some plants stockpile toxins to provide fast response to insect attack, others manufacture them as needed. When attacked, many plants respond by toughening up their cell walls in the area being attacked. Plants release various volatile compounds communicating with other plants and with insects (both the pests and predators of those pests). The example given is that when corn roots are attacked by a certain larva, the roots release a compound that attracts a nematode that is a predator of that larva. Sometimes, though, the attacker wins, as when certain beetles release their own volatile compounds in response to a plant’s compounds, signaling to other beetles to join the attack. Colorado potato beetles do this. This complexity calls our interventions into question: is it helpful to handpick the pests? Not if the pests call on comrades to join the fight.

Young sweet corn plants in July. When corn roots are attacked by a certain larva, the roots release a compound that attracts a nematode that is a predator of that larva. Photo Bridget Aleshire

If your soil is already healthy and rich in microbes, Sally thinks additions are not needed, including biostimulants, compost teas and foliar sprays to boost the numbers of beneficial bacteria and fungi. Biofungicides can prevent particular soil-borne diseases, but can’t cure them after the fact. Biofumigation is the process of growing a particular cover crop, chopping it finely and incorporating it into the oil, taking advantage of the allelopathic compounds released, to kill pests, diseases or weed seeds. Mustards, radishes and forage sorghum all have bio-fumigant properties.

The chapter on barriers, lures, traps and sprays includes recipes, and the caution that many homemade sprays kill beneficials as well as pests, as do some of the Organic commercial sprays like neem, Spinosad, quassia. Use these only as a last resort, and pay attention to dilution rates, time of day to spray and frequency of use.

Here you can find instructions for carefully treating seeds with a disease-fighting hot water treatment before planting. You can also find cautions, such as not heat-treating peas, beans, corn, cucumbers, lettuce or beets. Or old seed, as the germination rate might deteriorate too far.

Part 5 of the book is an A-Z of Pests and Disease. First are aphids – there are so many kinds of aphids! The lifecycle of aphids starts in spring with eggs hatching into wingless females that give birth via parthenogenesis to more females. Within a week, one female can produce 100 clones, which can repeat the process at the age of one week.  This continues until adverse weather or predators trigger production of a generation of winged female aphids that moves to new plants. Later in summer male aphids are born and females lay fertilized eggs that overwinter on host plants, to hatch the following spring.

Pepper plant with aphids. Photo Pam Dawling

Handpicking aphids is likely impossible, so start by blasting them off the plants with a water jet from a hose. This may decrease the population enough for natural predators to begin control. Failing this, a soap spray can be effective, although aphid predators will also be harmed. If you plant before any aphids arrive, you can use a fine mesh netting to keep them off, but monitor to make sure no aphids have got inside the net. You could try trap crops of nasturtiums to draw aphids away from your crop, but how much of your space do you want to devote to nasturtiums, and how do you deal with aphids then? The same choices of water and soap.

The list of pests continues through the alphabet. For some, nasturtiums can act as a repellent rather than a trap crop. Cucumber beetles are a good example. Nasturtiums are a brassica, and will attract cabbage caterpillars if there are no other brassicas around. There are two pages on making the garden inhospitable to slugs and snails and three pages of control options including beneficial nematodes, ducks, coffee grounds (acidic and non-specific) and iron phosphate pellets.  Finally, there are whitefly and wireworms.

The disease chapter starts with various blights, including two pages on potato blight (both types). Cankers, club root, damping off fungi, mildews, molds, rots, rusts, spots, scabs, viruses, and on with the sad list to end with wilts. It makes sense in an organizational way to end with the problems, but it makes for a sorry place to leave off.

This book is good on detailed info on soil micro-organisms and the general theme works globally. I recommend checking against local Extension Service or eOrganic before following any of the specific techniques, to ensure it’s likely to succeed where you live.

Haraka No-Till Rolling Punch Planter

The Haraka No-Till Rolling Punch Planter being used on untilled soil, following a rope on the ground for good alignment.
Photo Eden Equipment

More growers are trying no-till methods, and I have reviewed several no-till books: The Living Soil Handbook by Jesse Frost; The No-Till Organic vegetable Farm by Daniel Mays; The Organic No-Till Farming Revolution by Andrew Mefferd; and No-Till Intensive Vegetable Culture by Bryan O’Hara.

Good tools for small-scale no-till work are hard to find. This Haraka Planter has the possibility of providing a breakthrough, so although I don’t have much experience of it, I’m spreading the information.  I hope those who buy one and try it will leave a comment. [I’m not receiving any commission if you do buy one.]

Haraka planter in travel mode, from the left side, looking at the seed canister.
Photo Pam Dawling

The Haraka planter is a very sturdy South African punch planter made for small-scale farmers. Built in Africa for African farmers, and now also available in the US.

Haraka planter in planting mode. The operator stands behind the press wheel.
Photo Pam Dawling

It is made by Eden Equipment, and is used for large seeds such as corn, beans, peas, sorghum, soybeans, sunflower. It has a set of thick plastic plates for various seed sizes. We used the smallest hole size for Kandy Korn sweet corn (a fairly small-seeded variety). That gives you some idea of which seeds it can handle. Okra would work, I feel pretty sure. If sorghum and sunflowers work, how about squash, cucumbers and melons?

Haraka Planter seed plate and appropriate seeds
Photo Eden Equipment

It can be used on tilled or no-till plots. It can punch through crop debris and plastic mulch very effectively. [Be careful – I tried loading one into the back of a car with two flattened cardboard boxes protecting the seat. It punched right through the cardboard!] On their website there is a video and a link to a flyer. They claim it is the fastest manual planter available. It certainly makes steady progress, as you’ll see in the video. You can plant 1 hectare in 10 hours.

Pushing the Haraka planter.
Photo Pam Dawling

It does take some serious pushing – we tested it first in tilled soil and that was harder work than the soil which had not been recently tilled. See the video to understand the punching and hole-opening action of the sturdy points on the wheel.

Haraka planter on soil tilled a few weeks previously.
Photo Pam Dawling

You can add a draft animal or a second person pulling, to share the work, if very tough going. You can make and add concrete weights to improve soil penetration in situations with a lot of straw, or packed soil. You can see those in the photo below

The planter comes with an assembly manual that is fairly straight-forward. It uses black and white photos rather than diagrams, so it is a bit hard at a couple of points to determine what to do. I called in someone who already uses one to show me the two bits I was not understanding.

There is a planting mode and a traveling mode, where you flip the heavy tool over and run it on the packing wheel without engaging the planter moving punches. I was struggling to flip the tool over, but my farming friend showed me a way to flip it over sideways, rather than the end-over method I understood from the manual. Later I saw in this video one of the operators push it with his foot to start the flipping action and that was helpful.

Specifications:

  • In-row spacing: 300mm (fixed) (11.8”). You can make two passes, offset by 6” for closer spacing.)
  • Planting depth: around 45mm (1.8”)
  • Seed plate hole sizes: 5mm, 12mm, 14mm, 16mm (0.2, 0.5, 0.55, 0.6 inches)
  • Seed: maize, sunflower, soya, cow peas, sorghum, etc
  • Fertilizer: granular only: Place afterwards in a separate run
Eden-Equip-haraka-rolling-punch-planter

Eden Equipment also makes a Haraka fine seeder, which I have not seen. It is made for large scale vegetable gardens and small farms, and works in cultivated soil, not for no-till. You can download their flyer from the website. There’s also a video and lots of photos. Like the punch planter, it has a large steel wheel.

Specifications:

  • Planting depth: 0-20 mm (0.8”), adjustable
  • Calibration method: kg/ha (no seed spacing)
  • Seed: grass, small grains, Lucerne (alfalfa), radish, carrot, onion, etc.

For USA sales of both planters, contact Ben Johnston in Montevallo, Birmingham AL

[email protected] or [email protected]. Phone +1 (205) 503-3165

Workhorse Crops for July

Provider beans at the beginning of July.
Photo Pam Dawling

In this monthly series, I have chosen 14 Workhorse Crops (including two pairs) to focus on until April 2022: These are crops that we can rely on under a wide range of conditions. Some Workhorse Crops are easy to grow, some pump out lots of food, some are “insurance crops”, some are especially profitable (for those growing for market), and watermelons are simply the circus pony –  we all need fun!

I hope this series will help growers become more efficient, productive and profitable (if selling) as we expand our lives again. Perhaps you don’t have as much time at home as last year, but no need to give up growing your own food, just make some smart choices of less time-consuming crops and growing methods.

See my book review of McCrate and Halm’s High Yield Vegetable Gardening for ideas on labor-saving gardening methods

Workhorse Crops to Plant in July

In July here in central Virginia, the heat strikes hard, and the daylight has started to get a tiny bit shorter. This month we reach the peak of the year – next month we will really need to plan and execute our plans for a fall and winter garden. Most of our work in July is harvesting and weed control. In July we can plant 7 of our 14 Workhorse Crops, including the two pairs. It’s too late for asparagus, potatoes, tomatoes, watermelons, and winter squash.

July’s Last Chance Sowings – (more Last Chances in August).

We sow our last edamame 7/14 and our last sweet corn 7/16. We sow our last bush green beans 8/1-8/3, and zucchini, summer squash and cucumbers by 8/5 at the latest. If you are in a colder climate than ours, with a first frost earlier than our October 14, your last sowings of beans, zucchini, summer squash and cucumbers will be in July.

In July we still have time to sow fall crops that need 30-50 days to maturity, if we want to harvest them between mid-September and mid-October. For crops to harvest from late September to late October, we have time for those that take 30-70 days.

Beans: We sow bush beans every few weeks to keep up supplies of tender beautiful beans. See June’s Special Topic section for info about Succession Planting, to help you determine when and how often to sow beans, and how we control Mexican Bean Beetles that used to destroy our bean plantings. Our workhorse green bush bean is Provider. Bush Blue Lake comes a close second, and we often alternate them, with Provider for the 1st, 3rd, 5th sowings and Blue Lake for the 2nd and 4th. Provider is a little bit more cold-tolerant, and a little faster than Bush Blue Lake, at 50 days compared to 55.

Cabbage: Most brassicas will germinate fast at 86°F (30°C). The challenge is keeping the soil moist. For fall crops, we use an outdoor nursery seedbed and bare root transplants, because this works best for us. Having the seedlings directly in the soil “drought-proofs” them to some extent; they can form deep roots and don’t dry out so fast. Other people might prefer to sow in flats.

Fall brassica nursery seedbed with insect netting.
Photo Bridget Aleshire

To avoid flea beetles and harlequin bugs, we cover the beds until the plants are big enough to stand up for themselves against “pest bullying”. We like ProtekNet insect mesh on wire hoops. Overly thick rowcover or rowcover resting directly on the plants can make the seedlings more likely to die of fungal diseases in hot weather – good airflow is vital.

We aim to transplant most brassicas at four true leaves (3-4 weeks after sowing). In hot weather, use younger transplants than you would in spring, because larger plants can wilt from high transpiration losses. If we find ourselves transplanting older plants, we remove a couple of the older leaves to reduce these losses.

We sow cabbage (and broccoli, and some Asian greens to transplant mid-late July) in June and July. August is too late for us to start those.

Carrots: After May we hope not to need to sow more until the beginning of August. We have just finished harvesting our spring carrots and have them bagged in the walk-in cooler. Carrots grown in hot weather don’t taste that good, but home-grown hot weather carrots are still better than ancient carrots from thousands of miles away. If we have not grown enough carrots by the end of May to see us through to October, we sow in June, and even July if we must. We shade the beds.

Chard: Swiss chard can be sown here in July or August, for a nice fall harvest. It germinates best at 85°F (29°C). It grows big leaves within 50 days of sowing, and smaller ones after only 35 days. Chard is not plagued by flea beetles, and does not have problems germinating in hot weather like spinach does. Chard is the poster-child insurance crop!

We use chard for fresh greens in summer, transplanted into a hay mulch in late April. Organic mulches help keep the soil cool during hot weather, so are very helpful for leafy greens. This crop will be in the ground until mid-winter, and mulch will keep back most of the weeds.

Remember, chard is biennial, and will not bolt the first year (unless stressed by lack of water).  I’ve noticed the red chards bolt more easily than the green ones. I suppose red crops are a bit stressed already, as they are short of chlorophyll, compared to the green ones, making photosynthesis harder work.

Sweet corn: we make 6 sowings of sweet corn, to harvest from July 4 to mid-October.

To calculate the last worthwhile sowing date, add the number of days to maturity and the length of the harvest window (7-14 days), and subtract this number from your average first frost date. For our 10/14 frost date, using an 80-day corn as an example, 80+7=87 days, brings us back to July 19 for our final sowing date. In practice, because corn matures faster in summer than in spring, this calculation gives you a little wiggle room in case the first frost is earlier than average. You could add a little more wiggle-room to be more sure. We make our last sowing on July 16, when there are not enough warm days left in the season to mature another sowing.

Kale and collards We sow 6 beds of kale, two each, every 6 days, (8/4, 8/10, 8/16, 8/24) until we succeed in getting enough established. Often we’ll get patchy emergence and end up transplanting plants from one bed or one end of a bed to fill out the blank areas. If your climate is a colder zone than ours, you will be sowing kale and collards in July.

Young yellow squash.
Photo Bridget Aleshire

Zucchini (courgettes) and summer squash: another crop type that we succession sow, to get a continuous supply. We make five or six plantings, each one half yellow squash (Zephyr, Gentry) and half zucchini (TenderGrey, Noche, Golden Glory). Now the soil is warm (60°F/15.5°C), we direct sow. The time from sowing to harvest is only around 42-54 days. 8/5 is our last sowing date for zucchini, summer squash and cucumbers. We like Noche zucchini for a disease-resistant zucchini variety (diseases are worse here later in summer).

After sowing, we hoop and cover the row with insect netting (rowcover works if it has no big holes). We have many bugs that like these plants, especially the striped cucumber beetles, so we keep the rows covered until female flowers appear. At that point we need the service of the pollinators, unless the squash is parthenocarpic (sets fruit without pollination). We pack away the covers, hoe and thin the squash to 24” (60 cm). It would be better to thin sooner, but we rarely find the time.

Workhorse Crops to Harvest in July

Nine of our 14 workhorses can be harvested in July

Beans from early July/late June,

Cabbage is ready here from late May until mid-July. We store enough to feed us until we start harvesting fall cabbage.  For cabbage to store to eat over the summer, cut with a strong knife and set it upside down on the nest of leaves to dry a little. Come back along the row with a net or plastic bag and gather up the storage quality cabbages to refrigerate.

Our first sweet corn of the season. Bodacious
Photo Pam Dawling

Sweet corn: Harvest before daybreak for best flavor, because the sugars manufactured in the plant the day before become concentrated during the night. We’re not that dedicated. We harvest ours in the morning, and hurry it to the walk-in cooler.

Harvest may start 18-24 days after half the ear silks show, if the weather has been reasonably warm. Judging corn’s ripeness is a skill, based on information from many of the senses. The first sign we look for is brown dead silks. If the ear has passed that test, we investigate further. All ears should look and feel plump and rounded to the tip. Each variety is a little different, so close attention is needed. Some varieties exhibit “flagging” of the ear, meaning it leans away from the stalk as it matures and gets heavier. New crew can test for ripeness by opening the side of the husk with thumb nails, and puncturing a kernel: the kernels should look filled-out and squarish, not round and pearly; the juice should be milky, not watery or doughy. The advantage of opening the side of the husks is that it is possible to close the gap if the ear is not ripe, without risk of collecting dew or rainfall. If the ear is ripe, we bend it downwards, give it a quarter-turn twist, and then pull up away from the plant.

We harvest every other day, which balances getting the amount we need with not spending more time than needed picking. Such a schedule can work well for CSA farms. Other growers could well need to harvest every day, if daily fresh corn is what your market needs. Leaving a three-day gap risks poor quality starchy ears and a lower total yield.

Take steps to keep the crop cool while harvesting. Never leave buckets of corn out in the sun. Even at room temperature, harvested OP ears lose half their sweetness in 24 hours.

After harvest, cool the corn quickly. Hydrocool if you have a large operation: drench or immerse the crop in near-freezing water. Otherwise, simply refrigerate and keep the corn cool until it reaches the consumer.

Carrots perhaps, although we do intend to get all our spring carrots harvested and stored before the weather gets very hot.

Chard can be harvested whenever you want some. Simply snap or cut off some outer leaves and stand them in a bucket with a little water until you cook them. For sustainable harvesting levels, we use the standard leafy green mnemonic “8 for later” meaning that we make sure to leave at least eight of the inner leaves on each plant, as we harvest the outer leaves. With chard, we can take a couple more than this, but we don’t want to exhaust our workhorses!

Garlic in the north might get harvested in July, but here in the mid-Atlantic ours has been curing for several weeks and is now ready for snipping, sorting and storing. I wrote about garlic recently. Several people have written to ask about the nylon netting in our photos in those posts. We don’t remember where we got it. The sides of the squares/diamonds are about 1.5”. A reader sent this photo and she is using Tenax fencing. It’s sold for deer fencing and is very strong.

240 heads of garlic drying in Tenax fencing.
Photo Sierran Farmer

Potatoes, if planted in March, will be ready to harvest this month. If the tops have died, dig up a few samples and see if the skins rub off, or if they have thickened up enough for storage. It’s fine to dig some for immediate use, but for long-term storage, they need thick skins. This usually takes two weeks after the tops die. You can hurry up the process by mowing the tops to bring growth to an end. Then wait two weeks and test them.  I wrote about potato harvest last year.

Tomatoes are ready to harvest outdoors now. Wait for the leaves to dry from rain or dew, before touching the plants. To minimize the spread of fungal diseases. Lightly press the bottom of the tomato to make sure it is soft enough to be fully ripe. Snap the tomato off at the knuckle, so that the plant gets the signal the fruit has gone, and will ripen more.

Harvesting Zephyr summer squash, wearing a long-sleeved shirt.
Photo by Brittany Lewis

Zucchini and summer squash in our climate need harvesting every day, if we are going to avoid blimps. Summer squash can be twisted off the plants, but zucchini need to be cut. The hairs on the leaves, combined with sweat, can cause unpleasant itchiness. Wear long sleeves or make special sleeves for this job that are not attached to any particular shirt. Make a casing and insert elastic around the top edge (and the bottom, if there are no cuffs). These sleeves can be bought, but everyone probably has an old shirt and could make their own.

We harvest every day to the fall frost (or beyond if we remember to cover that last planting with rowcover on chilly nights.).

From storage: carrots and potatoes.

Workhorse Crops Special Topics:

Hunting Hornworms on tomatoes

I have written about hunting hornworms and Dealing with hornworms on tomatoes . Learn to recognize hornworms and the signs of their activity, as well as their parasitic braconid wasp.

Having determined there is a hornworm in the vicinity, the next task is to find it. They can grow to be 4″ caterpillars. You’d think it would be easy – a big striped caterpillar like that. Not so! They are the exact same shade of green as tomato leaves. Hornworms can look remarkably similar to curled tomato leaves. The white stripes mimic the veins on the undersides of the leaves.

When I find some signs, I gaze at the area, looking for discrepancies in the pattern – bare stems with lumps on them. Usually the caterpillar is on the underside of a chewed stem, and often (but not always) they have their heads raised. When you find one, get a firm grip, pull it off the plant (they have strong legs which hold on tight), drop it on the ground and stomp on it. The skins are quite thick.

If I still can’t see the worm, I stand still and sway a bit from side to side, viewing the plant from different perspectives. It helps if the top of the plant is back-lit, but I do always check both sides of the row, no matter where the sun is. Knowing the signs of hornworm grazing can save you time looking everywhere. Focus your attention on where you are most likely to find them, and you will get the most success in the least time.

A large tobacco hornworm.
Photo Pam Dawling

Tomato string weaving

(See my Mother Earth News blogpost How and when to string-weave tomatoes)

String-weaving (also known as basket-weaving or Florida string weaving) is an easy way to support lots of tomato plants. This method is ideal for long rows,. All you have to store over the winter are the stakes. No bulky cages or rolls of wire mesh. We have used it for all kinds of tomatoes, and some other crops.

The ATTRA publication Organic Tomato Production includes a comparison of different tomato support systems. You can also see this on the eXtension page Training Systems and Pruning in Organic Tomato Production

String-weaving comes equal-best or second best in almost all categories: yield, earliness, fruit size, quality, pest control and protection from sunburn. It is worst as far as labor cost, although it doesn’t seem so bad, as the labor is spread out through the season. Trellising with a high wire between posts, and strings to wind each plant around, comes out best for earliness, fruit size and pest control (but worst for cracking, and thus not so good for marketable yield). Cages are best for marketable yield (so people who only grow relatively few plants could choose that method). But caged tomatoes do poorly on earliness and fruit size. The cheapest support system is none at all – sprawing the plants on the ground. But the fruit quality and quantity is poor, (pests, rotting, cracking and sunburn reduce potential yields).

Tools for string weaving

Put tomato stakes in soon after planting, while the soil is still soft, and you can see where the drip tape is. We use 6’ (1.8 m) metal T-posts. Some people put an extra stake at an angle tied to the end stakes as a brace. Set one T-post after every two plants along the row. Our stringing tool made is a 2’ (30 cm) length of wood, with a hole drilled through near each end. Twine is threaded through one hole and back out the other. A length of plastic pipe could also be used (pipe doesn’t need holes drilled, as the twine can be threaded down through the pipe). The twine moves through the tool freely. The tool serves as an extension of the worker’s arm, to get the twine over tall stakes, and you can give it a quarter turn to pull the twine tight. For maximum efficiency, keep the tool in your hand all the time.

Tomato stake and Weave diagram from eOrganic

Our variation on string-weaving looks quite like the drawing from the Extension Service. We have a couple of tweaks that make string-weaving work even better. Our first trick is to park the bale of twine in a bucket at the beginning of the row and leave it there. No need to lug it with you! Stand between the working end of the twine and the slack being pulled out of the bucket – get yourself inside the loop when you start, to avoid tangles. The spare twine will be running out behind you as you work the first side of the row. You’ll use it for the return journey.

Tomato string-weaving step-by-step:

  1. When the plants are 12” (30cm) tall, tie the twine onto an end stake, about 8-10” (20-25 cm) above the ground.
String-weaving step 2: Using the stick tool to wrap twine round the post.
Photo Kathryn Simmons
  1. Pass the twine in front of two plants and the next stake and wrap the twine around the back of the stake, pull it tight, and twist the tool to help tighten it.
  2. Next, here’s our second trick: use the thumb or forefinger of your other (non-tool-holding) hand on the crossover to keep it tight, and loop the twine around the stake again, making sure that the second loop ends up below the first. This locks the twine so that if you let go, or later on a groundhog chews through your twine, the whole row doesn’t slacken.
Detail of string-weaving tomatoes: locking the twine by crossing the second wrap over the first.
Photo Kathryn Simmons
  1. Continue along the row to the end, then take the tool round to the other side wrapping the twine round the end post.
  1. Weave back along the other side of the same row, putting a row of twine at the same level as on the first side. You will need to flip the twine that was behind you on the first side over to your new working side as you need it. Once you reach the end, tie off the twine and cut it.

Close view of coming back on the second side of string-weaving.
Photo Kathryn Simmons

  1. You’ll see that you never actually wrap twine around a tomato plant, so there no injury from tight twine. The plants are simply held between two fences of twine that you “build” by making a new round once-a-week as the plants grow (every 8” (20 cm) up the stakes).
Showing the distance between rows of string-weaving.
Photo Kathryn Simmons
  1. At the end of the season, cut the twine each side of each post, and pull it out, then remove the stakes and till in the tomato plants.

Book Review: Pawpaws, The Complete Growing and Marketing Guide by Blake Cothron

Pawpaws: The Complete Growing and Marketing Guide by Blake Cothron, New Society Publishers, 2021, $29.99

“Blake Cothron is an authority on pawpaws, and provides a clear, detailed guide for commercial success in growing this “oddly appealing species” (his own words). The supply of this exotic, trending, easy-to-grow fruit has not yet met the demand. Blake shares the wealth of his knowledge, including challenges, and when he doesn’t know, he says so (and it’s probable that others don’t know either.)”

This is the advance praise I wrote for Pawpaws, now inside the front cover. Last fall I reviewed Michael Judd’s For the Love of Pawpaws, a permaculturist’s take on growing pawpaws among diversified crops. Blake’s book, while mainly intended for small-scale organic commercial growers, is equally useful for the backyard enthusiast. Blake ensures you have the information you need to choose what to grow, where to buy it, how to plant it, keep it thriving, prune and harvest. Depending on your scale, you can try the nine exquisite recipes here, or sell gourmet pawpaws online, or make value-added products such as craft brews, jams, and baked goods.

Blake and his wife Rachel Cothron, own Peaceful Heritage Nursery, a 4-acre USDA Certified Organic research farm, orchard, and edible plant nursery, near Louisville, Kentucky, the perfect climate for pawpaws.

America’s almost forgotten native fruit looks tropical and has an exotic appeal, but is an easy to grow temperate climate tree, and very cold hardy (US Winter hardiness zone 5, -20˚F/-29˚C). It is ripe for 4-6 weeks in late August-September. Although mostly grown in the South-east and Mid-Atlantic, pawpaws will grow in portions of 26 US states. Avoid confusion with the tropical papaya, which is sometimes also called pawpaw. The North American pawpaw is Asimina triloba.

The book is studded with cultural gems such as that you can sometimes locate the site of an old native American village by the clusters of pawpaws still growing there.

Blake Cothron

There are some false myths about pawpaws, including the idea that they are secretly tropical and related to bananas, papaya and mango, They are not. The second myth is that they grow best in shade. Also not true! They can grow in shade, but will not produce good fruit unless in full sun. A third myth is that they are ripe when blackened by frost. Oh no! They are usually ripe weeks before frost. Frost is not a benefit, but a cause of damage! (This myth is not true of persimmons either.) Another myth is that the flowers smell really bad. It’s just not true. Lastly, a myth that would be nice if true: pawpaws are not immune to all diseases and pests. Certainly they don’t suffer from as many health challenges as apples or peaches, but there are pawpaw troubles as Blake explains. All these stories show how important it is to have a trustworthy guidebook.

Wild pawpaws are found as thickets of suckers growing up from the enmeshed roots of older trees, or as clusters of seedlings around a mother tree. They may feed wild animals, but will not grow the large tasty fruits humans want. Suckers are clones of the mother tree, and as pawpaws are rarely self-fertile, these thickets do not produce fruit. For human food, pawpaw trees need full sun, well-draining soil and plenty of space. Not what you might have assumed. Read this book!

Wild pawpaws are most often found in moist lowland areas near water, but in well-draining areas, not swampland. They are often on sunny slopes (not northerly sides). They can be found along edges of clearings, trails and old roadways. In Kentucky, Blake reports about 25% of the wild pawpaws are tasty, 50% are edible and 25% are “spitters”. If you’ve experienced anything other than the top 25%, this book can be your encouragement to try some cultivated types.

When you buy pawpaw trees, go for potted 1-4ft grafted trees at $30-$50 each. These will survive for 15-20 years and provide harvests for 10-15 of those. During that time you can plan where and when to plant your next pawpaw grove. Cheap bare-root seedling trees will save you money, but they won’t earn you money or appreciative friends. Premium fruit comes from premium trees, well cared-for.

Pawpaw trees can mature at 20ft tall, or you can keep them pruned to be 7-15ft and avoid high ladder work. The diameter of a mature tree can be 20ft in full sun, with an attractive pyramid shape.

Peaceful Heritage Nursery,

When planning your orchard site, remember “the more sun, the more fruit”. 12-14 hours is best, but 7-8 hours of direct, strong, undiluted sunlight will be enough for a decent fruit set. Pawpaws are not too exacting about soil, apart from the need for good drainage. Soil can be improved, but heavy wet soils need improving years before planting!

If you plan to mow with a tractor, you’ll need to plant rows 18-20ft apart. Otherwise 15-18ft between rows and 8-12ft between trees in the row will be enough. You do need genetically different trees close enough to cross-pollinate.

There are three colors of fruit: yellow, orange and white, with the orange ones having the strongest flavors (“banana/honey/persimmon/pumpkin”). Yellow-fleshed cultivars have more of a “banana/cocoa butter/Mexican flan/nutty/marshmallow/caramel flavor”, very sweet, with an aroma of citrus, pineapple, cantaloupe and strawberry. The white-fleshed ones are the mildest, with a “vanilla/light banana/cantaloupe/coconut/tropical fruit” flavor and a high sugar content.

Pawpaw fruit should be creamy, not watery or hard. There should not be any bitter or unpleasant after-taste! Another feature to consider when choosing varieties is the seed-to-pulp ratio. Ideally the seeds will comprise less than 10% of the total weight. Wild pawpaws can be 50% to 75% seeds.

Page from Pawpaws by Blake Cothron, showing fruits and seeds. Photo New Society Publishers and Blake Cothron

Blake includes 57 pages of good, bad and interesting facets of all 50 cultivars he could find in 2020. Some are widely available, others need to be tracked down through the North American Pawpaw Growers Association (NAPGA) or the North American Fruit Explorers (NAFEX). Don’t rely on nursery descriptions, but use Blake’s notes, where he has worked hard to be fair and objective. This book costs less than one tree, and can save many mistakes!

Blake distinguishes between Early Ripening (Aug 20-Sept 5), Mid-Season (Sept 5-30) and Late Season (after Oct 1). The dates are for zones 5b-6b, and outside that area they offer a relative idea. There is a grading scale (incorporating different professional opinions) based on size, flavor, texture, reliability and yield. Choose As and Bs unless you have a good reason to do otherwise. Size grades are Jumbo (16oz+), Large (12-16oz), Medium (7-12oz) and Small (3-6oz). Commercial growers don’t mess with the little ones.

A matter to face with pawpaws is that eating under-ripe ones can cause nausea. Some people cannot tolerate cooked pawpaw, Some speculate that it is the combination of cooked pawpaw with grains (as in baked goods) that give them trouble. Be ready for these possibilities but do not let them discourage you (or potential customers!) There are also people who sometimes experience mild euphoria after eating pawpaws, without harm. The one thing to never make or consume, is pawpaw fruit leather! It can cause 24 hours of serious intestinal distress. This is the “warts and all” part of the book. Avoid these problems and enjoy everything else about pawpaws.

Thinking how to incorporate pawpaws into your diverse farming? You do need to keep the grass and weeds down somehow. Grazing, mowing or mulching are the usual methods. In damp eastern regions, mowing will need to be done once a month from April to October. Mulch needs to follow the 3:3:3 rule: 3ins deep, 3ft wide around each tree, keeping 3ins away from the trunk. Cardboard topped with organic mulch is one option. Landscape fabric is another. Wood or bark chips can work well.

Blake tells cautionary tales about planting a new pawpaw orchard and not providing irrigation. Climate change is making rainfall more erratic and we get both extremes of quantity.  There is no substitute for water in a drought, so install an irrigation system before you plant, or immediately afterwards. Once the orchard is established, you might not need to water much.  Blake recommends orchard tubing with two emitters per tree, providing a gallon of water per tree per day.

Pawpaws go dormant in winter, unlike some other fruits that can be planted in the fall in milder climates. Plant in spring or early summer, digging large holes, breaking up the edges of the hole, supplying amendments, and having mulch on hand. This book gives clear step-by-step instructions. Staked tree protectors are essential for trees shorter than 30ins (seedlings) or 18ins (grafted trees). One main purpose is to protect the young trees from UV radiation. Tubex and Blue-X tree shelters are suggested.

While the trees are young, you can use the aisles for something else, such as grazing, or growing hay or another crop. Whichever weed control method you use, you will need to hand weed the small inner circles around each tree, including clipping suckers coming up from the rootstock. This gives you an opportunity to study each tree up close and see how it’s doing.

The pests and diseases chapter is complemented by color photos. With pawpaws, there is still much that is not known (or was known and then lost). Insects that attack pawpaws do not usually do much damage, although the list is long and includes borers, stinging caterpillars, a webworm, a leaf roller, the ubiquitous Japanese beetle, slugs, snails aphids, mites, thrips, scale insects and the Zebra Swallowtail Butterfly.  Jeremy Lowe at VSU has a very good PowerPoint presentation with superb photos.

I have been fascinated by the ZSB since reading about it in Michael Judd’s book, where I learned that the butterflies arrive at the time the pawpaws flower. Since then, I’m on the lookout each spring. The pawpaw is the ZSB’s only host, so do not kill all their caterpillars in your pawpaw trees – they have nowhere else to live! The eggs are laid between June and August. The caterpillars, which grow to 2ins long, eat the leaves and the damage to young trees is a real concern. Blake recommends hand-picking the caterpillars and carrying them to a wild pawpaw patch, or to some mature cultivated pawpaws, where they do little damage. Also, avoid destroying nearby wasp nests as the Ichneumon wasp Trogus pennator is a predator of the caterpillars, and nature may balance out.

For many pests and diseases, the key to healthy trees is good sanitation, keeping a clean orchard floor (mulched or mowed, I don’t mean bare soil!), and removing diseased wood or leaves.

Deer bite off buds and young shoots, and rub their antlers on the trunks. Goats do not eat pawpaw trees, although they can do damage rubbing their horns against the trunks. Other large pests include raccoons, possums, small rodents, and sapsuckers (small woodpeckers).

Diseases include Phyllosticta leaf spot, a fungal pathogen., and a few others, including Black Spot (Diplocarpon spp) which strikes in rainy seasons.

The condition of the leaves will show you if your fertility program is adequate. Healthy leaves are a deep vibrant green and bigger than human hands. Young trees should make 16-24ins of growth each year after the first one, until they are mature. Fertilize heavily from March-June in zone 6.

Pawpaw fruit cluster.
New Society Publishers and Blake Cothron

The chapter on flowering stages and cold tolerance of each (information that is hard to find elsewhere) will save you from disappointment. See the helpful photos showing blossom stages. Unlike some tree fruits (apples, pears), pawpaws bloom over a period of time, resulting in flowers at different stages, giving insurance against all being killed by one frost. In zone 6 the very cold-hardy Velvet Bud stage, when fruit buds start to develop, is in mid-February and full bloom starts in early April.

Pollination is conducted by various flies, beetles including lady bugs and ants, and spiders. Not by bees. So for good pollination, plant insect-attracting flowers in your orchard. Fruit takes 4-7 months to mature.

Pawpaw trees begin to fruit in year 3-5, with 5-10lbs/tree and double that the next year. A mature tree will yield a bushel (30-40lbs). Harvesting needs to be done gently (no vigorous tree-shaking!). Use sharp bypass pruners and set the fruit in a single layer in cushioned boxes. Ship immediately or use refrigerated storage for a couple of days. If picked ripe but firm, pawpaws can be stored for 3-4 weeks under refrigeration. They won’t be as delicious as tree-ripened fruits.

You can sell pawpaws at 2-3 times the price of apples, maybe $5-10/lb. Because the demand is not widespread, do not rely on farmers’ markets. The marketing chapter suggests 8 channels for selling pawpaw fruit. You will need to provide information and an attractive display or stunning photos if selling online. Avoid the question “What do we do now with a hundred or even thousands of pounds of soft, dripping ripe pawpaw fruit?” by planning months or years ahead.

If selling remotely, make it really clear that pawpaws are only available to ship in August and September (or whatever is true in your region). Ship out only perfect unblemished fruit picked that same day, and ship only Monday-Thursday. Weekend shipping can go very wrong! Pack the fruit with enough lightweight packing material so that when you shake the box, nothing moves. (I learned this tip packing garlic for shipping.) Shipping fruit across the country is a strange business with a large carbon footprint. Consider if you have better options selling locally, including specialty groceries.

Sales to restaurants can work well, as long as you have clear agreements, including price ($1-$3 per pound). Be perfectly reliable, make the chef’s life as easy as possible. Deliver early rather than late if you can’t be on time.

One feature of modern pawpaw marketing is that currently most Americans prefer crunchy fruit (even crunchy peaches) and the pawpaw is far from crunchy. Describing the texture as similar to creamy avocados, but sweet, seems a promising approach.

You could sell fruit as frozen pulp (deseeded!) to restaurants, bakeries or breweries. You could make value-added products from the less-than-perfect fruit yourself. As well as the items mentioned earlier, don’t overlook the possibilities of ice cream, chutney, food supplement pills and jewelry made form pawpaw seeds. Find out about the Cottage Food Laws in your state. Blake recommends the Ohio Pawpaw Growers Association with 29 handouts about NA Pawpaws.

Aside from selling fruit, you could sell seeds, seedlings or grafted potted trees. Seedling trees can be unpredictable, but if you start with good parents, you improve the chance of getting good seedlings. You can use seedlings as rootstock for grafting, or sell them to people growing food forests where productivity is not the main concern.

Seeds removed from ripe fruits need to be washed, cleaned, sterilized, labeled, stratified at 35-45˚F for 90-120 days, ensuring they don’t freeze. Seeds are sown on their sides, and can take 6-12 weeks to emerge above the soil. 2-3 year-old seedlings are used for grafting rootstock. Grafting is fairly easy, and KSU has some very good free videos.

The book includes a pawpaw calendar, cost analysis and some troubleshooting. Tips include not to worry if your new trees only grow a few inches the first year. This is probably because growth is happening underground, establishing strong roots. It could be a sign of root damage during transplanting, so if you are about to plant more, improve your technique! Damage caused by sunburn, dehydration, nutritional shortages, attacks by beetles, sapsuckers, string-trimmers, Phyllosticta disease, borers, deer, and winter sun, are all covered.

The cost analysis deals with start-up costs (not minor when trees cost $30 each). For an acre containing 295 trees that’s $8,850. Tree protection fencing can add $1,376. Landscape fabric and irrigation together can equal the fencing cost.  Other smaller costs add in to a total close to $10, 700 for the acre. Try for a wholesale tree price between $15 and $25, and your total is more like $6,260.

Production costs are estimated by KSU at $1,650/acre; harvest and market costs at $6,200/acre, including labor for pruning and harvesting at $12.50/hr. Total variable costs come out at $8,400/acre. Gross returns could be $9,600/acre, if you sell wholesale at $1.75/pound. Don’t quit your day job yet, but pawpaws can be a good addition to an existing operation with compatible markets.

The two-page Pawpaw Orchard Calendar is a quick reference guide for annual maintenance, and the dates where you live may need to be as much as one month later in spring and one month earlier in fall. The resources section includes books, supplies, and groups, including Peaceful Heritage Nursery.

Blake has created a highly readable, enjoyable and very intensive exploration into the cultivation of North American pawpaw.” This book is practical, useful and fascinating.

Here’s a one-hour webinar from New Society Publishers:

Workhorse Crops for June

Farao early cabbage
Photo Pam Dawling

Workhorse Crops for June

I’ve chosen 14 Workhorse Crops (including two pairs) to focus on at the beginning of every month, until April 2022: These are crops that we can rely on under a wide range of conditions. Some Workhorse Crops are easy to grow, some pump out lots of food, some are “insurance crops”, some are especially profitable (for those growing for market), and watermelons are the circus pony among the workhorses, I admit, but we all need fun!

I intend for this series to help growers who want to become more efficient, productive and profitable (if selling) as we emerge from sheltering at home and expand our lives again. Don’t give up growing your own food, just choose some less time-consuming ways to do it.

Our May 5 sowing of bush beans on June 30.
Photo Pam Dawling

Workhorse Crops to Plant in June

June is another busy planting month here in central Virginia. Next month the heat strikes hard, and the daylight starts to get shorter, but this month we are still climbing the hill of the year. Ten of our 14 Workhorse Crops can be planted in June.

Beans: We sow bush beans every few weeks to keep up supplies of tender beautiful beans. See the Special Topic section for info about Succession Planting, to help you determine when and how often to sow beans and other short-lived warm weather crops. Also see the Special Topic section to read how we control Mexican Bean Beetles that used to destroy our bean plantings. Click this link to read about soaking bean seed, using inoculant, sowing through biodegradable plastic mulch using a jig, sowing sunflowers in our bean rows as place-markers when harvesting.

Carrots: I wrote a lot about carrots in the past year, when the monthly series was on root crops. See this post on preparing beds for sowing carrots, and weeding and thinning. Check out this post on flame-weeding, if you plan lots of carrot-growing!

We sow carrots in late February, then twice in March, once a month in April and May and after that we’d like to not sow more until the beginning of August. Carrots grown in hot weather don’t taste that good: there’s little sweetness and too many terpenes (the compound that in small quantities gives carrots their distinctive carrotiness, but can be overpowering if too strong.) But home-grown hot weather carrots are still better than jet-lagged travel-weary carrots from afar. You could use shadecloth over the beds. If we have not grown enough carrots by the end of May to see us through to October, we sow in June, and even July if we must.

Carrots under shade cloth in summer.
Photo Pam Dawling

Chard: The perfect insurance crop! We use chard for fresh greens in summer, when spring kale, collards, broccoli and cabbage have long bolted and been turned under so we can plant something else. We transplant our chard into a hay mulch in late April. Organic mulches help keep the soil cool during hot weather, so are very helpful for leafy greens. This crop will be in the ground until mid-winter, and mulch will keep back most of the weeds.

Chard provides leafy greens all summer whenever you need them, and you can ignore it when you have plenty of other vegetables! As a biennial, chard will not bolt the first year (unless stressed by lack of water).  I’ve noticed the red chards bolt more easily than the green ones. I suppose red crops are a bit stressed already, as they are short of chlorophyll, compared to the green ones, making photosynthesis harder work.

Potatoes: I wrote a special series on potatoes last year. Click the link to access the whole series, starting with planting in April. Here we plant in March and June. For our June-planted potatoes, we pre-sprout the seed potatoes for just two weeks (shoots grow quicker in warm weather than in early spring). To protect the planted potatoes from the summer heat, we hill immediately after planting, even though we can’t see the rows! Then we unroll big round hay bales down the field to cover all the soil. Potato shoots grow strongly, and can make it up through the extra height of the hills/ridges and through the 3” (7.5 cm) of hay. After about 16 days, we walk through the field, investigating spots where there is no sprout. We call this task “Liberating the Trapped Shoots”. Often the problem is just an overthick clump of mulch, and the shoot will be quite literally trapped (and completely white). We simply let he shoot see the light, and redistribute the over-thick mulch.

June-planted potato emerged through hay mulch.
Photo Pam Dawling

Sweet corn: we make 6 sowings of sweet corn, to harvest from July 4 to mid-October. We are well into corn-planting time, which continues until mid-July, when there are not enough warm days left in the season to mature another sowing. Remember: don’t plant a mixture of different corn genotypes, and don’t plant Indian corn, popcorn or any kind of flint or dent corn within 600′ (180 m) of your sweet corn.  This leads to very disappointing starchy corn. We grow only sweet corn in our garden, to avoid this problem.

Sweet potatoes: I wrote a lot about planting sweet potatoes in 2020. Wait for the soil to warm before planting out your sweet potato slips, they don’t grow well if too cold. We plant ours a couple of weeks after the last frost, around the time we transplant peppers and okra. In early June, we replace any casualties, if needed, to fill out the rows again. This year we have a beautiful looking patch, with rows of healthy plants on ridges, with biodegradable plastic mulch. We have a solar-powered electric fence to deter the deer. My latest worry is groundhogs, who can slip right under the electric fence. They haven’t yet, but I expect they will, if we don’t catch them first.

Sweet potatoes on biodegradable plastic mulch, with solar electric fence charger.
Photo Pam Dawling

Tomatoes: In mid-June we plant a bed of late tomatoes, to boost the yields when the maincrop beds start to pass their peak. We planted our main crop tomato beds at the very beginning of May, and they’re looking quite good.

Here’s a post about planting tomatoes in our hoophouse. We use the same techniques in the hoophouse and outdoors. We transplant one row of tomatoes down the centerline of a 4ft (1.2 m) bed, 2ft (60 cm) apart. Once the weather has settled so that we’re confident we won’t need rowcover any more, we stake and stringweave. We install a steel T-post every two plants (4ft /1.2 m) apart and start stringweaving when the plants are about 12ins (30 cm) tall. I’ll say more about stringweaving next month.

Watermelons: As I explained in May, I gave watermelon a “Circus Pony” place among the workhorses! They’re not easy, therefore not reliable, but they provide so much pleasure when they do grow well. We transplant our watermelons, to get ripe ones as early as possible.

Watermelons grow very well on black plastic mulch, which warms the soil as well as keeping weeds at bay. The first year we switched from using hay mulch to biodegradable plastic mulch, we were astounded to get ripe melons a full month earlier!

If you want to use organic mulches for warm weather crops, don’t do it immediately. Wait till the soil warms through. This year we made that mistake, then we had late cold weather and the transplants all died. We’re going to experiment with station-sowing seeds directly in the gaps. Station-sowing is a technique of putting several seeds in the ground at each spot (station) where you want one plant to grow. Rather than making a furrow and sowing a row that needs thinning later. It’s a good technique for remedial work (ahem!), or if growing very expensive seeds, or for crops you are not familiar with, such as parsnips. You see several seedlings all the same and can be pretty sure it’s the thing you planted.

Watermelons can be planted from seeds when the ground has warmed to at least 70°F (21°C). On average, it takes about 85 days for Crimson Sweet seedlings to mature and produce ripe fruit. This is late for us to sow watermelons, and we certainly won’t get early ones this year, but we could get them in September. Better than none.

I described transplanting watermelons last month, if you need that info.

Crimson Sweet watermelon.
Photo Nina Gentle

Winter squash are a true workhorse, and can still be sown here early in June, provided we don’t sow the slow-maturing ones like the gigantic Tahitian Butternut. Aim for harvesting in September and October and count back to see how many days you have until you want to harvest. Then choose the varieties that will have enough time. You can also transplant winter squash if you need to. We did this once when our fields flooded. It worked out fine.

We mostly grow Butternuts, Moschata types that store best. This is the type to focus on if you want squash with no damage from borers or cucumber beetles. The tougher stems are better able to repel invaders. They need warm growing temperatures above 60°F (16°C).

See last month’s post for more about sowing winter squash, and for other kinds of winter squash, such as some Maxima squashes that store quite well and have relatively high resistance to squash bugs compared to others in this group, and Pepo squashes, suitable for storing a few weeks only

A bee pollinating squash.
Photo Pam Dawling

Zucchini (courgettes) and summer squash: another crop type that we succession sow, to get a continuous supply. More about succession planting below in the Special Topic section. We make five or six plantings, each one half yellow squash (Zephyr, Gentry) and half zucchini (TenderGrey, Noche, Golden Glory). We grow our earliest squash in the hoophouse, setting out transplants at the beginning of April. Our first outdoor crop is also from transplants. After that, the soil is warm (60°F/15.5°C) and we direct sow. The time from sowing to harvest is only around 42-54 days.

After transplanting or sowing, we hoop and cover the row with insect netting (rowcover works if it has no big holes). We have many bugs that like these plants, especially the striped cucumber beetles, so we keep the rows covered until female flowers appear. At that point we need the service of the pollinators, unless the squash is parthenocarpic (sets fruit without pollination). We pack away the covers, hoe and thin the squash to 24” (60 cm). It would be better to thin sooner, but we rarely find the time.

Workhorse Crops to Harvest in June

We have mnemonics for harvesting: Monday, Wednesday and Friday might be the crops beginning with the plosive Ps and Bs: peas, beans, beets, broccoli, blueberries etc. Tuesdays, Thursdays and Saturdays would be the crops beginning with the hard K and G sounds: kale, corn, carrots, collards, cabbage, garlic scapes etc.

Other crops like asparagus, lettuce, cucumbers, summer squash and zucchini we harvest 6 days a week. Some, like cabbage, we harvest twice a week.

Asparagus can be harvested here until early in June. Every day for the 8-week harvest period, snap off at ground level all the spears above a certain length. We chose 7” (18 cm). This task is best done first thing in the morning, when the spears are crisp. Daily harvest will also remove asparagus beetle eggs, controlling the pest level.

Cabbage is ready here from late May until mid-July. We store enough to feed us until we start harvesting fall cabbage.  An early sowing of fast-maturing varieties (like Farao or Early Jersey Wakefield which can be ready in only 60 days) can be followed by harvests of slower varieties. When a cabbage is ready for harvest, the head is firm and the outer leaf on the head (not the more horizontal wrapper leaves) will be curling back. For cabbage to store to eat over the summer, cut with a strong knife and set it upside down on the nest of leaves to dry a little. Come back along the row with a net or plastic bag and gather up the storage quality cabbages to refrigerate. Gather any lower quality cabbages to eat soon. If you would like to get another harvest from the same plants, cut criss-cross into the stump. Small “cabbagettes” will grow and can be used raw or cooked. They won’t store.

Carrots can be ready about three months after sowing in spring, although you can get thinnings for salads sooner. Read here about harvesting carrots.

Chard is ready for harvest as soon as you decide the leaves are big enough. Simply snap or cut off some outer leaves and stand them in a bucket with a little water until you cook them. For a sustainable rate of harvesting with chard, always leave at least 6 of the inner leaves to grow.

Garlic harvest time will be soon if not already. I wrote about garlic last week.

Kale and collards can be harvested until they are bolting, as long as the flavor is acceptable. Our spring-planted ones are not bolting yet, but the fall-planted ones were tilled in a couple of weeks ago.

New potatoes could be dug here during June, if you don’t mind reducing the final yield. The flavor of new potatoes, with their delicate skins, is very special. As a child, I ate them boiled with mint, and topped with some butter.

Tomatoes start to ripen this month. Our hoophouse tomatoes have started to yield a small amount of Glacier, Stupice, Sungold and Amy’s Apricot.

 

Zucchini harvest.
Photo Brittany Lewis

Zucchini and summer squash are ready from the hoophouse early sowing since about May 20.  We are now (June 2) harvesting our first planting of outdoors. We harvest every day to the fall frost (or beyond if we remember to cover that last planting with rowcover on chilly nights.).

From storage: carrots, potatoes,

 Workhorse Crops Special Topic:

Succession planting, and Mexican bean beetles

Succession planting is a topic I have often presented at workshops, so rather than give you more words, I’m giving you the slideshow from 2019. Towards the end it includes information about dealing with Mexican bean beetles.

 

 

 

Everything You Want to Know About Garlic: Garlic Almanac and Phenotypic Plasticity

Silverwhite Silverskin garlic
Photo Southern Exposure Seed Exchange

Everything You Want to Know About Garlic:

Garlic Almanac and Phenotypic Plasticity

(How garlic adapts to its locality)

It’s garlic harvest season for many of us and I notice many growers are searching my site for information. Here are quick links.

Garlic signs of maturity from October 2020

Everything You Need to Know About Garlic includes all the links listed below here.

Much about garlic is to be found in my Alliums for the Month Series:

Garlic harvest.
Photo Twin Oaks Community
Other posts about garlic, starting with harvest:
Pulling garlic scapes.
Photo Wren Vile

Phenotypic Plasticity

Phenotypic plasticity of garlic refers to the changes to a garlic variety grown in a particular location. Genetically identical garlics can grow differently in different environments. Garlic reproduces asexually, the new cloves are all clones of the mother plant, with no new genetic material introduced. And yet, over time, garlic saved and regrown each year in a certain locality will adapt itself to that location, due to the particular soil type, water availability, local temperatures, latitude, altitude and cultural practices. For example, studies have shown that varieties grown in drought-prone areas can, over years, develop more drought-tolerance. Commercial cultivars can have the highest bulb yield under well-watered conditions, but drought will show up the adapted strains in a comparison trial.

Garlic Plants
Photo credit Kathryn Simmons

We have been growing our own strain of hardneck garlic for over 30 years, and it does really well here. Originally the seed stock was a bag of garlic from the wholesale vegetable market. This is the very thing we are told not to do, as it may introduce pests and diseases. Indeed, it may, but our original folly is now deep in the past, and we have fortunately seen no problem.

I was reminded about phenotypic plasticity, when a friend and neighboring grower reported that the seed garlic we had passed on to her was doing well and was mature a couple of weeks before the variety she normally grows.

From the 2004 work of Gayle Volk et al, Garlic Seed Foundation analyzing 211 garlic accessions, we have learned that there are many fewer genetically distinct varieties of garlic than there are named varieties. Of the 211 accessions in that trial, only 43 had unique genotypes. But garlic shows high biodiversity and ability to adapt to its environment. The same garlic genotypes in different environmental conditions can show different phenotypes. This demonstrates the high phenotypic plasticity of garlic, probably linked to its complicated genetics, which somehow compensate for lack of sexual reproduction.

Work done in 2009 by Gayle Volk and David Stern, Phenotypic Characteristics of Ten Garlic Cultivars Grown at Different North American Locations  addressed the observation that garlic varieties grown under diverse conditions have highly plastic environmental responses, particularly in skin color and yield. This is a very readable paper for non-academic readers. Ten garlic varieties were grown at twelve locations in the United States and Canada for two consecutive years to identify phenotypic traits of garlic that respond to environmental conditions. The purpose of the study was to determine which phenotypic traits are stable and which vary with location.

Inchelium Red softneck garlic – note the small cloves in the center.
Photo Southern Exposure Seed Exchange
  • Clove number, weight and arrangement, clove skin coloration, clove skin tightness and topset number, size and color stay true to variety independent of location.
  •  Mostly, varieties classified as hardneck types produced scapes and those classified as softnecks did not, but there were some exceptions.
  • Bulb size, bulb wrapper color and bulb elemental composition (flavor) are related to location, (the influence of the local environment, such as the weather in that production year and the soil mineral content), rather than variety. The intensity of the skin patterns is highly dependent on the location. Some general trends were noted, but no clear correlation was found. (Read the study for the details).
  • For good size, predictably colored and flavored garlic, buy seed garlic grown locally that yields well. When garlic is grown in similar conditions to those in which it was produced, yields can remain consistent or improve.

    Our softneck garlic in May.
    Photo Pam Dawling
  • Varieties that grow well thousands of miles away are not a guarantee of a good result in your garlic patch. They may not match the bulb size, shape, color and flavor listed in the catalogs.
  • When grown under the same environmental conditions, the leaf number before bolting, flowering date, the final stem length, the flower/topset ratio, and pollen viability vary from one variety to another.
  • Studies that compared bulb firmness, pH, soluble solids, moisture content and sugar content with appearance determined that many of these traits are independent of skin color across 14 garlic varieties.
  • Bulb size was highly dependent on growth location with northern sites producing larger bulbs overall than southern sites for at least half of the trial varieties. Regional differences between varieties with respect to bulb size were noted, but because the project had a limited number of sites, specific variety recommendations for different regions were not provided.
  • Bulb size and weight were positively correlated with soil potassium levels.
  • Bulb sulfur and manganese content (flavor) were correlated with soil sulfur and manganese levels.

    The famous Music garlic, a hardneck type – see the stem.
    Photo Southern Exposure Seed Exchange
  • The demand for high-quality fresh garlic is increasing as restaurants and consumers seek out local vegetables. Consumers are attracted to colorful, unique garlic varieties for different culinary uses. As variety name recognition in garlic increases, understanding which traits define particular varieties and which traits vary within cultivars, depending on environmental conditions, will be valuable for successful marketing of new garlic types.

Book Review: The Living Soil Handbook by Jesse Frost

Cover of The Living Soil Handbook by Jesse Frost

The Living Soil Handbook

The No-Till Grower’s Guide to Ecological Market Gardening, by Jesse Frost, Chelsea Green Publishers, July 2021. 304 pages, $29.95

Jesse Frost, the host of Farmer Jesse’s No-Till Market Garden Podcast, has now made a lovely how-to and why-to book for us. No longer do we need to imagine the pictures while listening to the podcasts! The book is generously illustrated with color photos, charts, and diagrams and also hand drawings by Jesse’s wife Hannah Crabtree. The text and photos make plain the experience behind the suggestions. A glance at the bibliography shows how deeply Jesse educated himself on soil biology, chemistry and physics – it’s a list of detailed articles, not a list of books. I was interviewed by Jesse’s collaborator Josh Sattin for Farmer Jesse’s podcast, in November 2019.

Jesse and Hannah farm at Rough Draft Farmstead in central Kentucky, winter hardiness zone 6b with 55” (140 cm) of annual rain on average. While writing the book, Hannah and Jesse moved farms, gaining road frontage for on-farm sales!

The book revolves on three basic principles of professional no-till market gardening: disturbing the soil as little as possible, keeping soil covered as much as possible, and keeping it planted as much as possible. The phrase “as possible” in each of the three principles remind us to be reasonable, and aware of the context. No-dogma is as important as no-soil-disturbance. Sometimes a short-term soil disturbance will ultimately create a healthier soil: you might need to incorporate compost or amendments, or break up compaction. We are not feeding the plants. Nor the soil. We are farming the micro-livestock.

Appendices include notes on cover crops (when to sow, what to pair each cover crop with and how to terminate it); valuable material on critical periods of competition (for weeds or interplanting); resources and chapter notes from world-wide sources.

The topics have been carefully teased apart and the chapters are digestible by busy farmers during the growing season. No need to wait until winter! There are things you can do in midseason to head in the direction of less tilling and more soil-nurturing.

The first section, “Disturb as Little as Possible” includes a fine primer on the science of living soil. (Now you can explain photosynthesis to an inquisitive child.) Don’t skip over this basic soil science. Understanding is the key to good stewardship. The carbon cycle includes plants absorbing carbon dioxide, making root exudates that stream out into the soil, where they feed microbes, which respire most of it back into the air. The plants are not sequestering carbon, as we might wistfully hope in these days of an overheating planet. They are cycling it. It is true that some of the carbon that plants pass into the soil does remain there, in the tissue and exoskeletons of dead organisms, especially when there is no tillage. Some carbon converts to a stable form holding soil particles together.

Most growers probably know that frequent rototilling damages the soil (especially at the same depth every time, or when the soil is too wet or too dry). Soil care can include disturbance of various human kinds. Silage tarps can cause compaction when they gather rain, snow or ice, and stay in place a long time. Microplastic particles can crumble off old tarps into the soil, where they can be eaten up by the microfauna. Polyethylene can prevent beneficial gas exchange between the soil and the air. The soil life also “disturbs” the soil, churning it. Be guided by your observations of your soil, not by a particular belief in a certain method.

The chapter on breaking new ground describes several ways to make a no-till garden from a lawn, pasture or old garden. Deal with any soil compaction up front, either mechanically, or with an extra growing season and big-rooted plants.

Start with the no-till methods Jesse and Hannah use most often. “Shallow compost mulching” involves keeping a 4” (10 cm) layer (not deeper) on bed surfaces year-round, topping up as needed. With a 4” layer, the roots can reach the soil quite soon. Their second preferred method is grown-in-place mulch. Terminate a thick stand of cover crop and plant into the mulch as soon as it has wilted down.

If you don’t need to till before starting your vegetables, you can mow at soil level, and cover with a tarp for two summer months or 3-5 winter months. If you are mowing in the fall, you could spread cardboard and compost to form the beds, then tarp everything until spring.

Silage tarps and plastic mulches can be particularly helpful during transition, to salvage beds when things go wrong, or as emergency tools when a mulch supply line collapses.

The second section, “Keep it Covered as Much as Possible”, discusses compost, mulch, cover crops, flipping beds (transitioning from one crop to the next) and path management.

Composts come in four types (recipes included):compost

  1. Inoculating composts are expensive, fine textured and biologically active. Vermicast (worm manure) is one example. Good for compost tea.
  2. Fertilizing composts such as composted poultry manure are fine textured nitrogen sources to use before planting.
  3. Nutritional composts supply organic matter, microbiology, nutrients, minerals, and ample amounts of carbonaceous material. They can be used in larger amounts.
  4. Mulching composts are high in carbon, maybe 20 C:1 N, and relatively low in nutrients.

Mulching retains moisture, prevents compaction, reduces weeds, provides habitat, provides foods for some creatures, and reduces the impact of heavy rain or heavy feet. Straw can be expensive. Hay gives better weed suppression, but may itself be a source of weed seed. Spoiled hay has fewer live seeds, comes at a better price, and is messier to spread. Hay is more nutritious for the soil than straw. You could solarize your hay bales for 3-8 weeks before spreading, to kill seeds.

Paper and cardboard give excellent occultation compared to loose straw and hay, and provide an effective mulch with less depth (easier for transplanting into).

Wood chips, sawdust and bark mulch can sometimes be free, from workers clearing under power lines. Tree leaves and leaf mold are nutritious materials for mulch or in compost. Cover crops may be mowed or crimped to kill them, usually leaving them in place as a newly-dead mulch.

Peat moss is controversial. Peat bogs are very effective carbon sequestering habitats, and based on this, we should not use peat without restoring the bogs. Coconut coir is sometimes used as an alternative to peat moss, but we are mining the thin tropical soils when we import it.

Plastic mulches stop weeds, warm the soil, and conserve moisture. Landscape fabric is durable, and some growers burn holes for transplanting certain crops, and reuse it many times. Organic regulations require plastic mulch to be taken up at the end of the growing season, and they do not accept biodegradable plastic mulches.

Jesse Frost

Chapter Five is about flipping beds (replacing one crop with the next). Chopping plants off at the surface and/or tarping are two main no-till methods.

Jesse provides a valuable table of no-till crop termination methods for 48 vegetables and herbs. Whenever possible, leave the crop roots in the soil. Some can be cut at the surface (lettuce, baby greens, cucurbits and nightshades), some need to be cut slightly below the surface (brassicas, beans, corn, spinach and chard) and most others are harvested as root crops. Roots are a valuable source of carbon and root exudates, and help air and water pass through the soil.

Flail mowers, weed whackers (with a bush blade rather than a nylon line), scythes, hoes and knives can all be used to cut down old crops, depending on the particulars. When a crop is terrminated, deal with soil compaction if needed, amend the soil, keep it damp, get mulch in place, and replant the same day if you can, to help preserve microbes. If the previous crop was a cover crop, your fertility is supplied by that, and no more amendments are likely needed.

Tarping (introduced into English by Jean-Martin Fortier as “occultation”) is an effective no-till method. Silage tarps can kill crop residues, warm the soil and germinate weed seeds, which then die in the dark. Prepare an area by mowing it close – it is important that the tarp is in close contact with the soil, to break the plant matter down quickly. Tarps need to be well battened down. Jesse tells us that 2600 square feet (242 m2) is about as big a piece as any one person will want to move.  Say, a 25 x 100ft (8 x 30 m) piece.

Leave tarps in place for two summer weeks, 3-4 weeks in spring and fall, and two months or more in winter. Avoid PVC tarps (contain endocrine-disrupting phthalates), be wary of polyethylene (may contain phthalates), but woven landscape fabrics are made from polypropylene, which does not contain phthalates.

Solarizing is a similar technique using clear plastic to heat the soil, kill weed seeds, disease organisms and crop residues. Bryan O’Hara in No-Till Intensive Vegetable Culture has popularized using old hoophouse plastic. Solarizing can produce temperatures of 125˚F (50˚C) compared with 110˚F (43˚C) under tarps. You may need only 1-3 sunny days to kill crop residues with solarization. Cover crops take about 7 days. The heat will not go deep in that time: more of the soil life will survive than with tarping. Good edge securing is vital for success.

The necessary (but less profitable) task of path management is next. The goal is to make pathways do work, retaining moisture, housing microbes, and generally contributing to a healthy environment. The first priority is to get rid of weeds.

Wood chips and sawdust can perform well as path mulches. Sawdust mats down into an effective weed-preventing layer, and 2” (5 cm) is often enough. Get sawdust in place ahead of leafy greens, so that it doesn’t blow into the crop.

Living pathways sound wonderful, but can be very challenging, and it’s best to start with a small trial. Choose a non-spreading grass or a mix of clovers, grasses and herbs. Mow every week until the path plants stop growing.

Another option is to grow cover crops in the paths, mow-kill or winter-kill them and leave the mulch in place. Timing is critical. The crop needs to be planted and harvested either before the cover cop grows very tall or after it is dead.

Section three, “Keep it Planted as Much as Possible” has three chapters: fertility management, transplanting and interplanting, and a gallery of no-till crops, pulling together various materials and methods.

Test soil organic matter each year. Jesse points out that although organic matter is largely dead organic materials, a truly living soil must contain a fair amount of it! 5-10% OM is a healthy percentage; more is not better. OM above 12% can cause water retention problems and poor aggregation. Seedlings can struggle to germinate and establish.

You can improve soil performance with compost, mulches, cover crops, gypsum for clay soils, and cultivated indigenous microorganisms (as in Korean Natural Farming). Use good inoculating compost or compost tea in the root zone. Microbes aggregate the soil into various sizes of crumbs, improving the soil structure.

Be careful using perennial cover crops as living mulch around cash crops – the yield is almost always reduced, and sometimes the quality is compromised too.

If you are running a compact commercial market garden, growing cover crops may be out of the question, and you will rely on outside inputs. With a slightly bigger plot you can grow cover crops before long-season food crops, and use outside inputs for intensive short-term crops. Larger farms may find cover cropping more efficient than large-scale mulching. Winter-kill, classically with oats and spring peas sown in late summer, will provide a light mulch for early spring crops.

Cover crops can be terminated by crimping at the milk stage and tarping. Jesse shows a crimping tool made from a bed-width board with a foot-sized metal hoop at each end and a string or rod as a handle. This is a variation on the T-post tool advocated by Daniel Mays in The No-Till Organic Vegetable Farm.

Crimping and tarping gives more flexibility on timing than does crimping alone. Crimping and solarizing can be even quicker. Crimping or mowing, then topping with cardboard and mulch compost is another method, if you have sufficient supplies. Plant a shallow-rooted crop in the compost layer, don’t bust through the cardboard unless you have let the cover crop die for a few days before covering.

For side-dressing long-season crops, Jesse uses the EarthWay seeder with the pea plate. This never occurred to me! Another surprise suggestion was to use silage tarps white side up, to germinate carrots in the summer! Check daily, and remove the tarp late in the day to save the tender seedlings from frying in the mid-day sun.

Interplanting is best approached cautiously, with small trials and good notetaking. Interplanting can cause lower yields and poorer plant health when combinations and timing are wrong. Measure yields and weigh the costs and benefits. Popping lettuces into random lettuce-sized gaps rarely goes wrong, and you might keep a tray of lettuce transplants handy at all times.

Peppers take 60-70 days before bringing in any money. If you plant an understory of lettuce, you can generate income much sooner, and the lettuce will be gone before the peppers need the space. Growing two crops together reduces the impact of a crop failure, and makes unprofitable crops more worthwhile.

Read about the critical period of weed control, when crops are most affected by competition from weeds, sister seedlings or an intercrop. Like other good mentors, Jesse is quite open about his mistakes. Don’t confuse tall plants with healthy high-yielding plants! They may be striving for better light. Seedlings suffer more than transplants from being out-shaded. Transplants are past perhaps half of their critical weed-free period before you even set them out.

Relay cropping is a method of adding in another crop after the first is established but before it is harvested. A sure-fire way of keeping living roots in the ground! With careful planning you can sometimes run a multi-crop relay sequence.

To implant these ideas firmly in our minds, Jesse discusses seven example crops, including varieties, seed quantities, bed prep, weed control, seeder, spacing, pest control, harvest, yield, intercrops, marketing, tips, and notable failures (no need to make the same mistakes!). The examples (carrots, arugula, garlic, lettuce, sweet potatoes, beets, and cherry tomatoes) can be extrapolated for almost anything else. I took notes: there’s always good tips to be learned from other growers. Buy the book, you’ll quickly save the price! And more of your growing can succeed!

I originally wrote this review for the upcoming June/July 2021 issue of Growing for Market magazine.

Success with Planting Sweet Corn

Success with Planting Sweet Corn

Sweet corn at sunrise.
Photo by Wren Vile

Very fresh home grown organic sweet corn is so delicious! There’s no denying that sweet corn takes up a lot of space, so if you are really short of land, you may decide to forego corn. On the other hand, corn doesn’t take a lot of work, so if you have the space, but are short of help, corn is a good choice. This information comes from my book, Sustainable Market Farming.

This post about sweet corn include an overview of our corn-growing, dealing with weeds, and my slideshow on Succession Planting

This one Growing Sweet Corn for the Whole Summer – Organic Gardening … is one I wrote for Mother Earth News Organic Gardening .

Don’t Set Yourself up for Failure – Understand Sweet Corn Genotypes

 You can skip this section if you are only growing one variety of sweet corn, no other kind of corn, and it is at least 250’ (76 m) from anybody else’s corn. Otherwise, before you plant (hopefully before you buy seeds), read this.

With most crops, cross-pollination with other varieties or types is only a problem for those growing seed. With sweet corn, the seed is the food crop. Failure to isolate genotypes can lead to starchy unpleasant-flavored corn. Hybrids are made by crossing OPs. Making hybrids does not involve genetic engineering!

Our late corn beside sweet potatoes.
Photo Ezra Freeman

Nearly all genotypes of hybrid sweet corn include one of two recessive genes, su or sh2. Cross-pollination with other corn groups will produce the dominant genetics of field corn (that starchy stuff!)

  1. Normal Sugary (su or ns) types of sweet corn have old-fashioned corn flavor but are sweeter than OPs, although the sweetness disappears fairly rapidly after harvest. Most can germinate well in cool soil.
  2. Sugary-enhanced (se) and Sugary Enhanced Homozygous (se+ or se-se) types are more tender than (su), and slower to become starchy after harvest. Most, especially the (se+) types, are sweeter than (su) types.
  3. TripleSweet Sugary Enhanced (se-se-se) corn was created to be sweeter than se-se.
  4. Super Sweet (sh2) (also known as Shrunken) varieties are very sweet and slow to become starchy. If not isolated from all other types of corn, they will be very starchy and disappointing. They have very poor cold soil germination. The kernels are smaller than other corns, giving this type its name. The seed needs careful handling, to prevent mashing between a seeder plate and the hopper.
  5. Synergistic (se-se-se-sh2) types are combinations of genetics from the 3 previous genotypes. Each ear has 75% (se) kernels and 25% (sh2) kernels. They are flavorful, tender and sweet, but only when they are ripe. If picked too soon, they are a watery disappointment.
  6. Augmented Shrunken: these newer types contain the sh2 gene and some of the tenderness from the se types.

Isolate these three categories by at least 250’ (76 m) from each other:

  1. Super Sweet/Shrunken sweet corn varieties (sh2);
  2. all other types of sweet corn;
  3. all other types of corn (eg popcorn, dent corn, field corn)

Instead, you can isolate by time, sowing on dates to achieve at least a 12-14 day gap between maturity of the different plantings.

Your neighbor’s GMO sweet corn will cross with your corn, if it’s close enough for the wind to bring the pollen in. “Bt corn” has been genetically modified by incorporating Bt genes (Bacillus thuringiensis) so the corn includes its own insecticide. There are many reasons not to grow GMOs, including the spread of random bits of genetic material by cross-pollination with previously non-GMO crops, and the likely consequence of Bt-resistant insects, so I won’t give them more space here.

Sweet Corn Varieties

Our first sweet corn of the season. Bodacious
Photo Pam Dawling

Most Open Pollinated (OP) sweet corns are noticeably less sweet than modern sweet corn, so consider hybrids. OP varieties also deteriorate faster after harvest than hybrids, becoming starchier. Luther Hill is said to be the sweetest OP variety.

Some catalogs  indicate which varieties are suitable for certain latitudes. (Corn flowering is day-length sensitive.) Johnnys has a “Dynamic Comparison Chart” for the sweet corn varieties they sell. Many companies run cold-germination testing, and can tell you which varieties that year have good potential for early sowings. Others can rot in cold wet soil.

We plant corn six times through the season, often with three varieties in each sowing, as shown here in our late corn.
Photo Kathryn Simmons

For our location, we rely on the first three genotypes, supplemented with some of the others for variety.

  • Bodacious, 77 day (se) yellow, great flavor for one this early;
  • Kandy Korn, 89 day (se) delicious yellow workhorse;
  • Silver Queen, 96 day (su) white long-time favorite with some drought-tolerance and insect resistance;
  • Luscious, 77 day (se-se-se) bicolor (organically grown, good cold soil emergence);
  • Tuxedo, 80 day (se) yellow (tightly-wrapped, earworm resistant);
  • Sugar Pearl, 72 day (se+) white (very early, on short plants);
  • Argent, 86 day (se) white (tasty with tight earworm-defeating husks);
  • Spring Treat, 66 day (se+) yellow, one of the earliest yellow sweet corns with good cold soil tolerance.
Silver Queen white corn when mature (with bug).
Photo Kathryn Simmons

Sweet Corn Crop Requirements

A pH of 6.0-6.5 is ideal. Very fertile soil is needed, including high phosphorus. P deficiency shows up as purple leaf tips and margins; N deficiency as pale spindly stalks, yellow leaf tips and shriveled kernel tips; Mg deficiency as white-yellow striping between veins, with older leaves reddish-purple, perhaps with dead tips. Corn is sensitive to deficiencies of zinc or copper, but less so to low levels of boron. When looking for deficiencies, it helps to know what is normal for that variety, and to also consider water shortage.

If you used legumes in the winter cover crop preceding your later sowings of corn, a good stand can provide all the nitrogen the corn needs (100-125 lbs/acre; 112-142kg/ha). When the legume reaches its flowering point, the nitrogen nodules on the roots contain the maximum nitrogen.

The number of rows of kernels on the cob is set five weeks after emergence (although each variety has a number that is usual, under good conditions). Ear length and number of plants with double ears is established nine weeks after emergence. There’s the feedback on your farm’s fertility plan.

Sweet corn needs warm soil. Catalogs usually indicate the soil temperature (measured at 9am) recommended for each variety. 50°F (10°C) is the absolute minimum, and applies to treated seed and OP or (su) varieties only. 60°F (15.5°C) is better for most, and 65°F (18°C) or higher is required by some varieties. Common phenology signs for the season being advanced enough to sow corn are that white oak leaves are the size of squirrels’ ears and that ragweed is germinating. For us the first corn sowing date is usually around April 26, which is also our average last frost date.

Corn has no tolerance of frost, but escape from a late spring frost is possible if the seedlings are less than two weeks old and not yet very tall, as the growing point may still be underground. Thus, in a spring that promises to be warm and dry, it is possible to risk an early planting as much as 2-3 weeks before the last frost date. Having some transplant plugs for a back-up helps reduce the risk level.

Emergence takes 22 days at 50°F (10°C), 12 days at 59°F (15°C), 7 days at 68°F (20°C), and 4 days at 77°F (25°C).       

Our third planting of sweet corn on the left, fourth in the middle, 5th (barely emerging) on the right.
Photo Pam Dawling

Sowing Sweet Corn

2oz/50’ (55gm/15m) or 1lb/400’ (370gm/100m) are generally required. The (sh2) types have more seeds for the weight, because the shrunken seeds are lighter than other types – 200/oz (7/gm), 2500-5500/lb (5600-12300/kg); 1lb/1250’ (118gm/100m).

Corn is usually grown in rows 36” (0.9m) apart. We sow fresh seed 6” (15cm) apart, and if using seed from the year before, we sow at 4” (10cm) apart.  Depth of sowing can vary with the soil temperature, being a very shallow 0.5” (1cm) in spring, to 1” (2.5cm) in summer when soils are warmer lower down and seeds benefit from the extra moisture.

Seedlings are thinned to 8-12” (20-30cm) apart. 8” (20cm) spacing is usually optimal in terms of using available light and maximum yield for the area.. Upper leaves get 7-9 times the light of lower leaves, therefore it is important that the upper leaves are in good condition, to photosynthesize well. The lower ones get much less light, so may be broken off for easier harvesting.

Young sweet corn plants after imperfect hoeing.
Photo Pam Dawling

Corn is wind pollinated (though you will find plenty of bees collecting pollen, regardless). For best pollination, plant in patches at least 4 rows wide. Inadequate pollination leads to ears with flat undeveloped patches among the kernels.

One of our sprinkler tripods, in a broccoli patch.
Photo Pam Dawling

Corn seed must have moisture to germinate. If you use a push seeder, irrigate after sowing. Because we sow small areas of many different varieties, and because people love to plant corn, we sow by hand. Our method has the advantage of delivering water right where the seed needs it. We measure and flag the rows, put out ropes on stakes along the rows, and make furrows (drills). The rope and its shadow make useful guides for keeping the rows straight. Next we have someone flood the drills with water from a hose, and we hand sow into the mud. After covering the seed and tamping the soil, we ignore the patch until the seed germinates. The watering in the furrow reliably provides enough moisture to get the plants up out of the ground. The ropes (about 12” (30 cm) above the ground) deter the crows, making it hard for them to land near the buried seeds. In recent years we have started using a seeder again, as the number of crows has worryingly declined.

We use overhead irrigation for corn. If you use drip tape, you might set out the tape, turn on the water for long enough to mark the soil with damp spots, then sow those spots with a jab planter.

Transplanting Sweet Corn

 It is quite possible to transplant sweet corn, so those in marginal climates don’t need to give up hope. We usually prepare some plugs the same day we sow our first corn outdoors and use these to fill gaps at the first cultivation. We use 200-cell Styrofoam Speedling flats (1”, 2.5 cm cells). We float these in a tank of water until we set them out. Some vegetable seedlings would drown if continuously in water, but corn does not. It is important to transplant the corn before the plant gets too big, and the taproot takes off. 2″-3” (5-7.5 cm) plants seem OK. The plugs transplant easily using butter knives.

I’ll write about Growing Great Sweet Corn in about a month.

 

Vegetable Garden Tips

 

Young Yukina Savoy plants.
Photo Ethan Hirsh

My virtual workshop on Asian Greens 

is available from Mother Earth News Fairs Online here.

The Food Independence Course Part Two  consists of eight video presentations, most of which come with pdf handouts. My contribution is Growing Asian Greens, and pairs nicely with the Guide to Asian Vegetables by Wendy Kiang-Spray, author of The Chinese Kitchen Garden: Growing Techniques and Family Recipes from a Classic Cuisine. Other topics include Dandelion Wine, Homemade Teas, Food Conversations, Passive Solar Greenhouse Design, Productive Growing from Home, and Growing Your Own Spices.

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Decoy Cabbage White Butterflies.
Photo Good Seed Co

Easy DIY Cabbage Butterfly Decoy!

The Good Seed Co blog posted this lovely idea for protecting brassicas from those white butterflies Pieris rapae. It’s based on the discovery that the butterfly is territorial. If it sees a slightly bigger competitor it flies away. I have not tested this system, but it sounds like an interesting and fun project that costs next to nothing.

http://goodseedco.net/blog/posts/cabbage-butterfly-decoy Posted 25th Jun, 2015 in On Our Mind by Robin Kelson

PageOfCabbageMoths_efile

Cut out paper decoy representations of the butterfly. Here’s a single page template you can download

We don’t have many cabbage butterflies  because we have both a predator – the paper wasp, and a parasite –  Cotesia glomerata, a parasitic wasp that lays its eggs in small (first instar) larvae of the Cabbage White Butterfly, or Imported Cabbage Worm (as we call it in the US). Cotesia larvae emerge from the caterpillars after 15-20 days and spin yellow or white cocoons on or near the host which dies when the wasps emerge. We often find clusters of these cocoons (about the size of cooked rice grains) on the underside of brassica leaves.

I learned from Bryan O’Hara in  No-Till Intensive Vegetable Culture that our friends, the Cotesia glomerata wasps that parasitize brassica caterpillars, and overwinter as pupal cocoons on the undersides of brassica leaves, will hatch out in spring on the very day the overwintered brassicas start to flower. The 20-50 day lifecycle needs brassica flowers, so don’t be in a hurry to cut down all your bolting greens! The flowers provide nectar for the adult wasps. The leaves, as we know, provide food for the caterpillars, which provide the host for the wasps to lay eggs in. The wasp larvae feed on the caterpillar until it dies, then pupate.

There’s an incredible National Geographic video of this cycle, showing parasitic wasp larvae swimming around inside a caterpillar, bursting out through its skin. The weirdest bit is that it is the dying caterpillar that spins the protective cocoons around the pupating larvae. And us who plant the brassicas that feed the caterpillars! Who is the farmer and who is farmed?

This video shows a paper wasp tackling a caterpillar.

This one shows Cotesia glomerata emerging

This one shows more about the parasitic Cotesia glomerata 


Savoy cabbage with frost. Savoys can take much colder temperatures than this!
Photo Lori Katz

Average First and Last Frost Dates

Harvest to Table has this helpful article:

Average First and Last Frost Dates for Cities, States, and Countries

Average frost dates – the last one in spring and the first one in the fall – are useful to know when planning your crops. Once you’ve calculated your planting out date for various crops, you can work back to set sowing dates for the crops you’ll transplant, and bed prep dates for every crop. You can also make a co-ordinated plan that paces the work and doesn’t have too much in any one week, or any while you plan to be on vacation. You can calculate your first sensible planting date for each crop, your last one and perhaps some in-between ones to keep up supplies throughout the season.

You can use your average first fall frost date to make sure you don’t plant frost-tender crops too late in the season when you have no hope of them maturing in time for a harvest. You can extrapolate beyond the frost date to figure out when to harvest the more hardy crops. See my Winter-Kill Temperatures chart for useful tips.

By looking at the number of frost-free days in your area you can see whether to grow long-season tender crops like watermelons, or whether it’s only worthwhile if you choose fast-maturing varieties.

The Harvest to Table website is a trove of clearly explained information.

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Soil thermometer with easy-to-spot backing in a bed of beets.
Photo Bridget Aleshire

Soil Temperatures

Average frosts are only averages. Actual frosts can sometimes happen two weeks either side of those dates. Frosts are only one particular temperature, and may not matter to the crop you’re planning for. Soil temperatures for germination and for planting are another important part of planning.

K-State Extension has a brief article on the importance of measuring your soil temperature.

The Empress of Dirt has a helpful list of Best Soil Temperatures for Sowing Vegetable Seeds, in alphabetical order by crop.

Harvest to Table also has a list, ranked by temperature, so you can see what you can plant this week.

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Scottish Climate Friendly Farming Video

Farmer Patrick Barbour, from Highland Perthshire, has won the search for Scotland’s climate friendly farming champion. Patrick’s innovative three-minute video entry, filmed at Mains of Fincastle, near Pitlochry stunningly illustrates the benefits of tree planting, species rich grassland, rotational grazing for cattle and sheep and stitching nitrogen fixing crops into pastures.  It is available to watch at: Next Generation Climate Change Competition

Patrick, Robert and Catherine Barbour of Mains of Fincastle, near Pitlochry
Photo The Scottish Farmer