Favorite posts of 2023: soil, winter, garlic, melons, beans, aphids

I’m hunkered down on this rainy January day, in expectation of high winds and lots of rain. I’ve battened down the hoophouse and I’m working to get a blog post out before the electric coop’s warning of possible extended power outages comes true!

One of many wheelbarrows full of compost we spread on our raised beds every year.
Photo Wren Vile

In the past year, my top post has been Soil Tests and High Phosphorus Levels. Clearly a worrying topic for those who like me, once though compost should be applied as generously as possible. I wrote this post in 2017, and it’s still an issue many people want to learn about.

The second highest number of views goes to Which Vegetables are Genetically Modified (GMOs)? Another worrying topic.

Ugly, but not dead yet! Tokyo bekana outdoors on January 7, 2024 after several cold nights, at least two at 20F, two at 18F, one each at 15F and 12F. Photo Pam Dawling

In third place  is Winter-Kill Temperatures of Cold-Hardy Vegetables 2021, and in fourth place is Winter-Kill Temperatures of Winter-Hardy Vegetables 2016. The 2018 version is in 8th place. My highest number of views in a single day came when Texas had that awful very cold weather, in mid-February 2021, and farmers and gardeners needed to find out in a hurry which crops to try to protect, which to give up on, and which needed no attention.

Fifth place goes to one of my many garlic posts: Garlic Scapes! Three weeks to bulb harvest. Scapes, the flower stems of hard-neck garlic, are an underappreciated auxiliary crop. They are not just a freebie extra, but removing them helps the garlic bulbs grow bigger. Pulling scapes would be worthwhile even if you didn’t use them.

Pulling garlic scapes.
Photo Wren Vile

Cover Crops in Summer is number 6 in popularity. Sunn hemp is joining our list of favorites, along with buckwheat and soy.

Root Cellar Potato Storage comes in at number 7. That’s from 2018. Root cellars haven’t changed!

Crates of potatoes in our root cellar.
Photo Nina Gentle

Harvesting Melons is next. I remember when I didn’t know what “full slip” meant. I found out and decided to make a post, reckoning many other people didn’t know either. That’s a heritage post! From 2012, the year I started this site.

Young bush bean plants.
Photo Pam Dawling

Green Beans All Summer is close behind. The post includes an unusual method of planting bean seed through plastic mulch, as well as early season and late season beans, and scheduling sowings for continuous harvests all summer.

Growing Flowers to Attract Aphid Predators rounds out the list. The post includes info and photos of many annual flowers we tried for our hoophouse. Most of them did not flower early enough to deal with the January and February aphids that have no ladybugs to eat them. We have established several perennial yarrow plants, and have hopes for those this year. We’ve also come to appreciate the value of bolted brassicas, such as tatsoi, turnips, and senposai. Their flowers do attract beneficials.

Leave a comment if your favorite didn’t make the top ten, or if there is a topic you’d like me to cover, or update, or give more details on.

Cover Crops for July: Millet and Sorghum-Sundangrass

Focus Cover Crops for July:                     Millet and Sorghum-Sudangrass (Sudex)

In July we are very much looking for cover crops that will grow in hot weather. Last month I wrote about sunn hemp, with some notes about other hot weather legumes. This month we are turning our attention to good hot weather grass cover crops. Warm weather grass cover crops we use include Sorghum-Sudan hybrid (Sudex), and the millets.

Next month I will discuss winter-killed winter cover crops before early spring vegetables and undersowing winter-hardy cover crops in standing vegetable crops.

Also see my post Cover Crops in Summer for much more information, including  making space, sowing small spaces and finding time for the work.

Don’t sow a winter cover crop yet. If sown too early, oats head up in the fall and even drop seed. Only sow oats or barley in July in southern regions if you are sure you can get them turned under before they seed. They will not mow-kill.

Cover crop seeds are usually easier to find and cheaper at a local feed store, rather than online. Also you’re likely to find a regionally-adapted variety. But, of course, you may not find USDA Organic seed there. Be careful buying feed-grade seeds (rather than seed-grade), as they can contain weed seeds including GMO canola.

Variation in spring field corn root development at harvest following various summer cover crops. Preceding cover crop from left to right: sunn hemp (residues mulched in), pearl millet without fertilizer, sorghum-sudangrass, corn, pearl millet with fertilizer, and sunn hemp (residues harvested). Credit: Z. J. Grabau, UF/IFAS

Types of millet

Millet has good insect resistance and is relatively free of diseases. Read the descriptions below and especially the final height, the days to maturity and whether or not it mow-kills at any stage. See Working with the time you have left in the post Cover Crops in Summer. Avoid the trouble I had battling pearl millet with small walk-behind equipment, having to mow it frequently to keep it manageable.

German/Foxtail Millet

Foxtail millet seed heads.
Photo Eden Brothers Seed Supply

Setaria italic, 3-4’ (1-1.3 m) Fast growing annual (60-70 days). 75-90 days to seed formation. Not frost hardy. Mow-kills or roll-kills reliably after heading.

Sowing date: Needs warm soil. From 2 weeks after last frost onwards. Growth is considerably less if sown after summer solstice – day-length sensitive.

Sowing rate (US): Drilled:20 #/ac, Broadcast:30 #/ac, B:1-1.5 oz/100 ft2

Sowing rate (metric): D:22 kg/ha, B:34 kg/ha, B:3-4.5 gm/m2,

Uses and Cautions: Can be followed by late summer and fall crops. Fairly well-behaved – unlikely to become a weed. Easier than most other millets to incorporate.

Notes: Small seeds need good seedbed and few weed seeds. Fairly drought-tolerant once established. Shallow roots.


Japanese Millet

Japanese Millet
Photo Hancock Seed Company

Echinochloa esculenta 3-5’ (1-1.6 m). Fast growing annual, 45 days. Not frost hardy. Foxtail type, grown more in the north. Cannot mow-kill or roll-kill reliably.

Sowing date: From corn planting date. May and early June are best in the mid-Atlantic. Can be sown until early July, but growth is considerably less if planted after summer solstice because it is day-length sensitive.

Sowing rate (US): D:15-25 #/ac, B:35 #/ac, In mix with soy:54 # soy:12 # millet/ac, B:2 oz/100 ft2

Sowing rate (metric): D:17-28 kg/ha, B:40 kg/ha, In mix with soy:60 kg soy:14 kg millet/ha, B:6 gm/m2

Uses and Cautions: Can be followed by summer and fall vegetable crops.

Notes: For best re-growth, mow at 60 days when 3’ (1m) tall, and before heading. Cut to 3-8” (8-20 cm) and repeat every 40 days after that. If cut after heading, it will flower again in 2-4 weeks on short stems and set seed. Tolerates drought and wet soils, including cold wet soils.

Browntop Millet

Urochloa ramosa (L.) Nguyen. 2-5’ (0.6-1.5 m). 50-60 days. Cannot mow-kill. Foxtail type, grown more in the south.

Sowing date if last frost is 4/30, first frost 10/14. May – August

Sowing rate (US): D:20-30#/ac, B:30-40 #/ac, B:3 oz/100 ft2

Sowing rate (metric): D:22-34 kg/ha, B:34-45 kg/ha, B:9 gm/m2

Notes: Tolerant of acidic soils, low fertility and flooding.

Proso/Broomcorn Millet

Jean Hediger grows Proso millet on her Nunn, Colorado farm
Photography courtesy of Jean Hediger

Panicum miliaceum, More than 5’ (1.6 m) 60-90 days to maturity.

Sowing: Optimum soil temperature ranges from 55°F-65°F (13°C-18°C)

Sowing rate (US): D:20 #/ac, B:30 #/ac

Sowing rate (metric): D:22 kg/ha, B:34 kg/ha

Uses and Cautions: Can be followed by summer and fall crops. Seed heads may shatter once the topmost seeds are mature.

Notes: Cut after 60 days before it gets tough. A much finer textured grass than Pearl or Japanese millets. Makes a good mulch.

Pearl/ Cattail Millet

Pearl Millet
Photo USDA i7wiafe6

Pennisetum glaucum or P. Americanum, 5-10’ (1.6-3.2 m) Fast growing, 60-75 days. Not frost hardy. To winter-kill and avoid seed formation, sow 60-85 days before expected frost.

Sowing date: From corn-planting date until 60 days before fall frost. Soil temperatures of 75-90°F (24-35°C) are ideal.

Sowing rate (US): D:15#/ac in 18” rows, B:25-40 #/ac, B:1-1.5 oz/100 ft2

Sowing rate (metric): in 45 cm rows, B:28-44 kg/ha, B:3-4.5 gm/m2

Uses and Cautions: Can be followed by summer and fall crops. Or by early spring crops, if winter-killed.

Notes: Does OK in poor soils. Does not tolerate water-logging. Excellent biomass, even if sown in late summer, as it is not day-length sensitive. Mow before heading for fast regrowth. After heading it is fairly easy to mow-kill, although not as easy as German and Japanese millets.

How to broadcast seeds

To broadcast seeds, you can buy a shoulder-bag with a hand-crank that shoots out the seeds. Or you can develop a manual technique: take a handful of seeds from a bag or bucket you carry with you. Fling the seed confidently in front of your body in a wide fanning motion. Use a loose touch, don’t grip the seeds! Aim for about two seeds per square inch—but don’t worry if you don’t hit that goal. Broadcasting seeds is an art, and the exact density and pattern doesn’t matter.

While you are learning, try seeding half the crop walking in one direction, and then repeat at 90˚ to your original direction. After seeding, rake the seeds in, aiming to bury most of them ½-1” (1-2 cm) below the surface, but don’t sweat the details. Next, especially if water is in short supply, roll or tamp the soil so that the seed is in good contact with the soil, which will help it get the water it needs rather than drying out in an air pocket. Then irrigate with rain, a hose or a sprinkler to keep the soil moist until germination. Drip irrigation won’t do it.

EarthWay push seeder.
Photo from EarthWay

Alternatively drill the seed by hand with a hoe, or using a seeder. See VABF Using Manually-Operated Seeders for Precision Cover Crop Plantings on the Small Farm. Don’t worry if the seed ends up deeper than ideal. It will still germinate.

Sowing millet in mixes

See No-Till summer cover crops. A mix of soybeans or southern peas and foxtail millet can be grown during the summer and mow-killed (after heading), before planting in the fall. Garlic perhaps?

Mixes can generally be sown at a depth of 1” (2.5 cm), regardless of seed size. Major ingredients for a summer mix could include soy, southern peas and buckwheat. Lesser ingredients could include pearl millet, proso millet, radish, turnips, sunflowers and sunn hemp.

  • When legumes and grasses are mixed, sow on the date for the grass.
  • When 2 grasses are mixed, reduce the seeding rate of each by a third.
  • Do not reduce the seeding rate of legumes in mixtures.

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Taking down large cover crops

Don’t grow sorghum-sudangrass unless you have tractor-mounted equipment. Even some of the millets are quite large. Before planting, have a plan for how you will terminate the cover crop. You don’t want to delay getting your fall vegetable crops established.

On a small scale, most gardeners mow cover crops down, or pull them, and use for mulch (chop-and-drop) or compost. It may be that composting produces a more balanced soil amendment compared to incorporating raw residues directly into the soil.

If you avoid incorporating the cover crop, you can plant the next crop right away. Some cover crops (such as Sorghum-Sudangrass) produce allelopathic substances that can temporarily inhibit the germination of seeds, meaning you have to wait three weeks to plant.

If cover crop residues are left on the surface rather than incorporated, the rate of decomposition is slowed. Some N is lost to the air (denitrification), but the increased organic matter can increase the diversity of micro-organisms at the surface. 80% of the carbon from cover crops is below the top 8” (20 cm), where almost all soil data are collected. Remember the value of the roots!

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Sorghum-Sudangrass

Sorghum-Sudangrass hybrid/Sudex grows 5’-12’ (1.5-3.6 m) tall in 60-70 days and produces an impressive amount of biomass.

  • It cannot be mow-killed. It is not frost hardy.
  • Sow ½-1 ½” (1-4 cm) deep (less deep than corn). Plant seeds 1.5” (4 cm) apart in rows 8” (20 cm) apart (for best weed-suppression), or up to 36-42” (90-110 cm) apart.
  • Sowing date: From 2 weeks after corn-planting date (needs warm soil) and anytime onward until six weeks before frost. In zone 7, mid-May to late August. Plant earlier at your own risk – I think we’ve had some success despite the warnings.
  • Sowing rate (US): Drilled:25-40 #/ac, less if rows 36-42” apart. Broadcast:40-50#/ac. Broadcast:2 oz/100 ft2
  • Sowing rate (metric): Drilled:28-56 kg/ha, less if rows 90-110 cm apart Broadcast:45-56 kg/ha, Broadcast:6 gm/m2
  • Sorghum-sudangrass will smother weed competition, and make big improvements to the soil texture and the levels of organic matter.
  • Fast growing, deep rooting.
  • Good in preparation for new strawberry beds.
  • Suppresses root-knot nematodes, soybean cyst nematode and annual ryegrass.
  • After it’s established, sorghum-sudangrass is highly drought-resistant and thrives in summer heat
      • Sorghum-sudan cover crop after mowing to encourage regrowth.
      Photo Kathryn Simmons

    When the sorghum-sudangrass reaches 4’ (1.2 m) tall, cut it down to 6”-12” (15-30 cm) to encourage regrowth and more, deeper, root growth that will loosen compacted soil.

  • The cut tops make a good long-lasting mulch, in place, or to haul elsewhere.
  • Good ahead of fall crops if given 8-10 weeks of growth.
  • Winter-killed Sorghum-Sudan can be followed by early spring crops.
  • Sorghum-sudangrass roots exude allelopathic compounds that suppress pest nematodes and inhibit small seeds (weeds and crops) from germinating and even inhibit the growth of tomatoes, lettuce, and broccoli.
  • Wait at least 6 weeks after incorporating sorghum-sudangrass before planting a susceptible crop in the same spot.
  • Does well in mixes with buckwheat, soy, and/or viney legumes.
  • Can mix 10 # with 50 # southern peas/ac (11 kg with 56 kg southern peas /ha).
  • Sunn hemp and sorghum-sudangrass grow well mixed together. Try a 50:50 mix to start with. This mixture can increase overall biomass and the diversity benefits soil microorganisms and therefore nutrient cycling.
  • Be careful if feeding to livestock. Read up about prussic acid poisoning from this cover crop. Young plants (less than 24” (60 cm) tall) and those stressed by drought or killed by frost, can cause prussic acid poisoning. Ducks, geese and goats enjoy the forage.
  • It’s undeniable that Sorghum-Sudangrass can be hard to incorporate once tall, unless you have tractor-based equipment. It is too massive to tackle with small mowers or weed whips.

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Secondary Cover Crops in July

In July, legumes such as sunn hemp, soybeans, southern peas, and Partridge pea are good legumes to consider. See June’s post for more about those and also Senna Ligustrina a native perennial legume. Another option is summer, if you have a weedy area or suffer with nematodes or foliar fungal diseases, is solarization.

Solarization

Solarizing with clear plastic. Photo Pam Dawling

Solarization uses clear plastic (old hoophouse plastic is ideal) to kill pests, diseases and weed seeds near the surface of the soil by covering the soil for six weeks or more in hot weather.

If you are solarizing to kill weeds, you can see when they are dead. Bryan O’Hara poked a thermometer probe through solarization plastic and found a 50F degree (28C) difference between the outside air and the soil immediately under the plastic; a 10F (6C) difference at 1″ (2.5 cm) deep and little temperature gain lower than that. Solarization does not kill all the soil life below the surface level!

Extension offers Solarization and Tarping for Weed Management on Organic Vegetable Farms in the Northeast USA which can, of course, be modified for those of us in other regions.

Nematodes

I’ve written here before about our struggles with root knot nematodes in our hoophouse, and you can read everything I know about nematodes in my book The Year-Round Hoophouse. Nematodes are only active in warm weather, and we have not had problems with them outdoors yet, but of course, it’s warmer in the hoophouse!

Cucumber roots with nematodes (see circles).
Photo Pam Dawling

My article on nematodes in Growing for Market  in November 2014 describes our discovery of the beasties and our first attempts to deal with them. My most thorough blogpost about nematodes was for Mother Earth News  Managing Nematodes in the Hoophouse.

Good news – great hoeing weather! Bad news – more nematodes in the hoophouse August 2014 includes a photo of our first attempt at solarizing – a  bit of a How Not To! There is info on dealing with nematodes from Garry Ross in Hawaii, where nematodes are a fact of daily life, in my post Cold weather, snow, thinking about nematodes from February 2015.

Warm-weather cover crops that resistant or deter nematodes include sesame, Iron and Clay cowpeas, some OP French marigold varieties (but avoid Tangerine Gem or hybrid marigolds); chrysanthemum; black-eyed Susan; gaillardia (blanket flower, Indian blanket); a sesame/millet mix, sunnhemp, partridge pea, California poppy. Some of these require a long growing season to achieve much. See Solarization and crop choices to fight nematodes.

 Cover Crop Planning

My book Sustainable Market Farming has a chapter on cover crops and 9 pages of charts about particular options.

Cover of managing Cover Crops Profitably book from SARE

The book Managing Cover Crops Profitably (third edition) from the Sustainable Agriculture Research & Education Program (SARE), is the best book I know on the subject. You buy the book for $19 or download it as a free PDF from SARE.

See Harvey Ussery in  Four Outstanding Cover Crops for Summer.

“Too often, gardeners practice cover cropping only in the off-season — for instance, to protect soil in winter — and assume it’s not a summer option. But it is, and planting summer cover crops provides big payoffs.

We too often think gardening reduces soil fertility, but in fact, the more you keep live plants growing, the richer your soil will become. Roots exude substances that feed beneficial soil organisms, including the amazing mycorrhizae (see Mycorrhizal Fungi: The Amazing Underground Secret to a Better Garden). Deep-rooted plants draw minerals from subsoil, which makes the minerals available to shallow-rooted crops. Dead plants, including invisible roots, decompose and release nutrients for use by subsequent crops. Plants also prevent soil erosion, and decomposing roots open channels for oxygen and rain, and provide pathways through which earthworms and other important organisms can migrate. Repeated seasons of organic matter deposition will increase soil carbon, or “humus,” which is crucial to soil fertility, friable texture and water retention.”

 

Cover Crops for June – Sunn hemp

 

Sunn hemp flowering in November at Nourishing Acres Farm, NC. Photo Pam Dawling

Focus Cover Crop for June: Sunn hemp

Last month I wrote about buckwheat. For small areas that will be needed back in production soon, buckwheat continues to be a good choice, unless irrigation is in short supply. You don’t get much biomass from buckwheat in a drought!

In June we are mostly looking for cover crops that will grow in hot weather. One we have recently started to use in our hoophouse is Sunn hemp (Crotalaria juncea). It looks promising as an outdoor cover crop here too. Sunn hemp is not at all related to cannabis – don’t smoke it.

Sunn hemp, a tropical legume, can grow as tall as 9’ (2.7 m) in as many weeks.  It needs 8-12 weeks frost-free to grow to full productivity. In the US it is grown as a summer annual, except in Hawaii, where it can be grown to seed at lower elevations. With adequate moisture, temperature and fertility, researchers have recorded a growth rate of 1 foot per week. It comes from India, where it is grown for fiber production and as a forage, as well as a cover crop. It is recommended for warm season use in US hardiness zones 8-13, but has been successfully cultivated as far north as Washington State.

Sunnhemp cover crop at Nourishing Acres Farm, NC.
Photo Pam Dawling

Benefits of growing sunn hemp

If you sow sunn hemp in a summer gap between spring and fall vegetable crops, it will provide a nitrogen boost for the fall crop, because it is a legume. Also, as a branching vertical plant, it avoids the problems of sprawling legumes. In dense plantings, it can fix more than 120 lbs (54 kg) of nitrogen and 12 pounds of biomass per 100 sq ft (0.56 kg/sq m). It can fix over 100 lbs of nitrogen and produce over 5000 lbs of biomass per acre (112 kg/ha and 5604 kg/ha respectively).

Most studies of vegetables grown following sunn hemp have found higher vegetable crop yields, because of the nitrogen boost, and the large amount of biomass increasing the soil organic matter. The large production of biomass means it is useful as a way to sequester carbon. The well-developed root system with a strong tap root also provides erosion control.

Sunn hemp suppresses weeds and also conserves soil water, storing summer rainfall for fall crops, and reducing runoff. Sunn hemp may enhance soil microbiota. Sunn hemp residue contains allelochemicals, that inhibit or delay germination of weed seeds and small crop seeds. Because of this, do not sow small-seeded crops or cover crops for several weeks after incorporation.

Sunn hemp suppresses plant-parasitic nematodes such as root-knot (Meloidogyne incognita) and reniform (Rotylenchulus reniformis) nematodes by producing allelochemicals that disrupt nematode life cycles. It promotes the growth of both antagonistic microorganisms and beneficial nematodes. Pest nematode numbers can be reduced for several weeks after incorporating sunn hemp into the soil. (I was disappointed to read “weeks” rather than “months” as I was hoping, although the EDIS ENY-717(see resources section) offers “a few months”)

Variation in spring field corn root development at harvest following various summer cover crops. Preceding cover crop from left to right: sunn hemp (residues mulched in), pearl millet without fertilizer, sorghum-sudangrass, corn, pearl millet with fertilizer, and sunn hemp (residues harvested).
Credit: Z. J. Grabau, UF/IFAS

Sunn hemp can be grown as a wind break to protect sensitive vegetable or flower crops, or young trees. Mow or cut the sunn hemp at 60 days, or lop the tops, to prevent too much shading.

Sunn hemp seeds at the start of a seed germination test. Photo Pam Dawling

Sowing sunn hemp

Sow sunn hemp starting a week after your sweet corn sowing date, up to 9 weeks before your first fall frost, when it will die. A soil temperature of 68°F (20°C) or more is good. It tolerates a wide range of soils (but not if waterlogged), doing better in poor sandy soils than most crops. Water for the first two weeks of growth, but do not overwater.

Plant inoculated seed (use the same inoculant as for southern peas) up to 1” (2.5 cm) deep, with seeds 1.5” (4 cm) apart in the row, and with rows 6” (15 cm) apart. Sowing densely (as with all cover crops) will work better to smother the weeds. On a field scale, drill at 25-50 lbs/ac (28-56 kg/hectare), or broadcast at 40-60 lbs/ac (45-68 kg/ha).

Another opportunity is to sow sunn hemp in the late summer or fall, 7-9 weeks before a frost. The frost-killed mulch covers the surface for an early spring food crop planting.

Sunn hemp seeds germination test. Photo Pam Dawling

Sowing sunn hemp in mixes

Sunn hemp and sorghum-sudangrass grow well mixed together. Try a 50:50 mix to start with.

This mixture can increase overall biomass and the diversity benefits soil microorganisms and therefore nutrient cycling. Only grow this very tall cover crop mix if you have tractor-based equipment. It is too massive to tackle with small mowers or weed whips.

Sunn hemp can also be mixed with other legumes, such as American joint vetch (Aeschynomene americana), southern peas (Vigna unguiculata), hairy indigo (Indigofera hirsuta), and slender leaf rattlebox (Crotalaria ochroleuca). This list comes from Florida and may not apply where you live. The shorter height of northern sunn hemp varieties, such as day-neutral ‘AU Golden’ and ‘Ubon’, may work better for cover crop mixtures. ‘Crescent Sunn’ is a short-day variety which will carry on growing if sown out of season.

Growing sunn hemp

Sunn hemp is fairly drought-tolerant from two weeks after germination, and requires little care. For maximum growth, irrigate until 75% of the plants are flowering (perhaps at the end of the third month), then you can stop irrigating.

Cutting the crop back at less than 60 days after sowing stimulates branching (more biomass) and more root penetration (better drainage). In our hoophouse, we have used hedge shears to do this at a nice ergonomic elbow height. Cutting at around 60 days produces long-lasting mulches that increase soil carbon. After 60 days, the stems thicken and become fibrous and high in cellulose. It is best to mow Sunn hemp before 90 days, due to the toughness of the fiber, making it hard to incorporate.

On a field scale, a roller-crimper can be used to break the plant stems, leaving a layer of mulch suitable for no-till transplanting of fairly large transplants. The sunn hemp is killed by crimping, and does not regrow.

A long bed of sunn hemp in November at Nourishing Acres Farm, NC. Photo Pam Dawling

Challenges with sunn hemp

Sunn hemp is notorious for seeds that are high in toxic pyrrolizidine alkaloids. Ingesting lots of seeds can cause damage to the liver, lungs, heart and nervous system. Susceptibility depends partly on the animal species: pigs are most vulnerable, followed by chickens, horses, cattle and sheep. Goats have the lowest risk.

Tropic Sun has reduced levels of these alkaloids, and is non-toxic to poultry and livestock. This and other southern varieties may be less tolerant to cold climates than northern varieties such as AU Golden and Ubon. AU Golden may flower 5-6 weeks after sowing

In some states (in 2005, Arkansas for example), Sunn hemp is regarded as a noxious weed, so do check the rules where you are, at your local NRCS office, Extension Service or state agricultural service. Some Crotolaria are noxious weeds, but as sunn hemp will not set seed consistently north of 28° N latitude (slightly north of Corpus Christi, TX), it has little potential for becoming a weed.

Deer and rabbits may browse on sum hemp, and some moths and pod boring insects may attack the stems, leaves or seedpods.

Sunn hemp growing in southern Florida.
Credit: Qingren Wang, UF/IFAS

More resources on sunn hemp

USDA Sunn hemp Plant Guide, 2005:

Ask Ifas: Questions and Answers for Using Sunn Hemp as a Green Manure Crop

EDIS SL 306 Sunn Hemp – A Promising Cover Crop in Florida

EDIS ENY-717 Management of Nematodes and Soil Fertility with Sunn Hemp Cover Crop.

NRCS USDA 1999 Sunn Hemp: A Cover Crop for Southern and Tropical Farming Systems

USDA Plant Materials Program

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Secondary Cover Crops in June

In my May post I mentioned secondary cover crops such as soy, mustard, sunn hemp, and southern peas. I explained why we don’t grow mustards as cover crops (too many brassica food crops, too many harlequin bugs).

If you have only 28 days until the patch is needed for a food crop, you can grow mustards or buckwheat. Or weeds, if you’re careful not to let them seed!  If you have at least 45 days, you can grow soy or Japanese millet.

In June, legumes such as soybeans, southern peas, and Partridge pea are other good legumes to consider.

Soybeans as a cover crop
Photo agcrops.osu.edu

Soybeans are a great summer cover crop and they are also a legume, so they add nitrogen to the soil. They have good shade tolerance and tolerance to foot traffic (that is, people harvesting crops on either side). Because of this, we like using soy to undersow in sweet corn.

Iron and Clay southern peas as cover crop in the hoophouse, smothering weeds.
Photo Pam Dawling

Southern peas are another warm weather cover crop option. They are also a legume, and so will add nitrogen to the soil. Iron and Clay is the sprawly variety best known for cover crop use, but other varieties also work.

Senna Ligustrina, a native perennial legume, is another warm season cover crop possibility. I was given this suggestion last September by a reader in Florida. She suggested I look for a senna native to my region. Ernst Conservation Seeds sells Maryland Senna, which tolerates wetlands and dry roadsides. The idea here is to find a plant adapted to your region, meaning it will grow well. The other side of the coin is that if you are growing annual crops, you will need to pay attention and prevent self-seeding, unless you are able to cope with the chaos.

At Ernst Conservation Seeds, they “grow, process, and sell hundreds of species of native and naturalized seeds and live plant materials for ecological restoration, sustainable landscaping, reclamation, wetlands, and natural resources conservation.” If you are looking for some less usual cover crops seeds, this is the place to turn to.

Next month I will write about sorghum-sudangrass and the millets. If you are in a warmer climate than I am (central Virginia) or you want to consider more options, those are good hot weather grasses. Also see my post Cover Crops in Summer for much more information, including  making space, sowing small spaces and finding time for the work.

If you have only 28 days until the patch is needed for a food crop, you can grow mustards or buckwheat. Or weeds, if you’re careful not to let them seed!  If you have at least 45 days, you can grow soy or Japanese millet.

Cover Crop Planning

My book Sustainable Market Farming has a chapter on cover crops and 9 pages of charts about particular options.

The book Managing Cover Crops Profitably (third edition) from the Sustainable Agriculture Research & Education Program (SARE), is the best book I know on the subject. You buy the book for $19 or download it as a free PDF from SARE.

Harvey Ussery  Four Outstanding Cover Crops for Summer.

ATTRA Cover Crop Options for Hot and Humid Areas

Cover Crops for May: Buckwheat

Buckwheat in flower in September.
Photo Pam Dawling

This is the first of a monthly series on cover crops, which will take us through a whole year, to April 2024.

Why Grow Cover Crops?

<a title=”USDA, Public domain, via Wikimedia Commons” href=”https://commons.wikimedia.org/wiki/File:Soil_food_webUSDA.jpg”><img width=”512″ alt=”Soil food webUSDA” src=”https://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Soil_food_webUSDA.jpg/512px-Soil_food_webUSDA.jpg”></a>

See my post Cover Crops in Summer.

  • Cover crops suppress weeds and provide a boost to soil organic matter.
  • Keep live roots in the ground as much of the time as possible, to feed the microorganisms in the Soil Food Web.
  • Here is a diagram of the Soil Food Web: https://upload.wikimedia.org/wikipedia/commons/8/89/Soil_food_webUSDA.jpg
  • Roots anchor the soil, preventing erosion in heavy rains.
  • Dead roots also have a role, providing drainage channels in the soil and letting air in deeper.
  • Adding organic matter to the soil is a way of sequestering carbon, as well as providing nutrients for your crops.
  • Deep-rooted cover crops draw up nutrients, bringing them up where crop plants can access them.
  • Leguminous cover crops provide nitrogen, saving imports of organic fertilizers or a big compost-making operation.
  • Too often, gardeners grow cover crop only in the off-season, to protect the soil in winter, and assume it’s not a summer option. But it is, and planting summer cover crops provides many benefits.

Focus Cover Crop for May: Buckwheat

A bed of young buckwheat with a cosmos plant to attract beneficial insects. Photo Pam Dawling

I have a blog post Buckwheat, a wonderful summer cover crop, introducing an article I wrote for Growing for Market magazine. See that post for basic details I mostly won’t repeat here.

Buckwheat (Fagopyron esculentum) is a fast-growing warm-season broadleaf annual that is a very useful cover crop. Its special strengths are in weed-suppression, attracting beneficial insects, improving the soil tilth (aggregate structure) with its fibrous roots, and extracting potassium, calcium and phosphorus from the soil to the benefit of following crops. Buckwheat is almost three times as good as barley in scavenging phosphorus, and more than ten times better than rye (a poor phosphorus scavenger). Because buckwheat is not related to any of the common food crops, it is simple to include in rotations.

Buckwheat can be sown up from your last frost up to 35 days before first fall frost. Buckwheat can close its canopy in just two weeks, preventing the soil baking in summer conditions. Because it matures quickly, and self-sows, it can be used in several successions with tilling between, to suppress some perennial weeds.

Flowering buckwheat in September.
Photo Pam Dawling

Buckwheat can do fairly well on poor soils, is tolerant of a range of soil pH and is an easy crop to deal with manually or with small-scale equipment. Even mature buckwheat plants are easy to deal with using manual or small-scale equipment. You can just pull up the plants by hand, or use a hoe or scythe to slice them off at the soil line. You can chop them into the soil, or gather them up and compost them. Or you can use a no-till method, let the dead plants die into a surface mulch and plant through them.

Buckwheat yields only a couple of tons per acre, but does it in only six to eight weeks. If you want to increase the (admittedly sparse) biomass, cut down buckwheat just before it reaches 25% bloom, to a height above the lowest leaf node. Buckwheat will regrow rapidly and you may even be able to make a second cutting.

Buckwheat also makes good food for poultry or rabbits, and chickens love the seeds. It does not provide good forage for larger livestock.

Beds of young buckwheat.
Photo Bridget Aleshire

Barbara Pleasant, in her 2009 article Cover Crops, described Rhizodeposition as a special advantage of using cover crops. Many plants release sugars and other substances through their root hairs into the soil. They are solar-powered pumps, sending energy down into the soil, causing the root tips to host colonies of useful microorganisms. As the roots move deeper, the microbes follow. With vigorous winter cover crop plants, like oats or rye, this process goes on down to 6 feet (much more deeply than you should dig). Buckwheat doesn’t go very deeply at all, but it can be working for you, which is much better than leaving the soil empty and drying out.

Buckwheat in flower in June. Photo Pam Dawling

Buckwheat Resources

Secondary Cover Crops for May

Soy, mustard, sunn hemp, southern peas are all also good summer cover crops, and I will say more about them in the next few months. See Cover Crops in Summer.

Sunnhemp cover crop at Nourishing Acres Farm, NC.
Photo Pam Dawling

Sunn hemp, a nitrogen-fixing legume from the tropics, can grow as tall as 9’ (2.7 m) in a few months. Sow sunn hemp from a week after your sweet corn sowing date, up to 9 weeks before your first fall frost, which will kill it. It tolerates a wide range of soils (but not if waterlogged). Plant inoculated seed (use the same inoculant as for southern peas) 1” (2.5 cm) deep, with seeds 1.5” (4 cm) apart in the row, and with rows 6” (15 cm) apart. Sowing densely (as with all cover crops) will work better to smother the weeds.

If you sow sunn hemp in a summer gap between spring and fall vegetable crops, it will provide a nitrogen boost for the fall crop, because it is a legume. In dense plantings, it can fix more than 120 lbs (54 kg) of nitrogen and 12 pounds of biomass per 100 sq ft (0.56 kg/sq m). 60 days after sowing, the stems thicken and become fibrous and high in cellulose; cutting at this stage produces long-lasting mulches that increase soil carbon. If you cut the crop back at a younger stage, this will stimulate branching (more biomass) and more root penetration (better drainage).

Sunn hemp cover crop at Nourishing Acres Farm, NC
Photo Pam Dawling

We have taken to sowing sunn hemp as a summer cover crop in our hoophouse, and lopping it periodically with hedge shears to an ergonomic elbow height. This is because we don’t want it to shade crop plants further back (north). The fallen tops make a nice “forest floor” carbonaceous mulch.

Mustard we don’t grow as cover crops, although I do have experience of growing it in England, where it is one of the favorite cover crops for short crop gaps, or in preparing areas reclaimed from pasture or lawn. We have too many harlequin bugs, and we hope to break their lifecycle by having a summer month without any visible brassicas. (We do often have fall brassica seedlings growing under insect netting.) Also, our “crop portfolio” has plenty of brassicas already, and we’d rather have a better rotation, with brassicas less often.

Mustards can decrease weeds, or certain pest nematodes, if you grow the right kind.

Soybeans as a cover crop
Photo agcrops.osu.edu

Soybeans are a great summer cover crop and they are also a legume, so they add nitrogen to the soil. They have good shade tolerance and tolerance to foot traffic (that is, people harvesting crops on either side. Because of this, we like using soy to undersow in sweet corn.

Southern peas are another warm weather cover crop option. They are also a legume, and so will add nitrogen to the soil. Iron and Clay is the sprawl variety best known for cover crop use, but other varieties also work.

Iron and Clay southern peas flowering in September. Photo Pam Dawling

Cover Crop Planning

My book Sustainable Market Farming has a chapter on cover crops and 9 pages of charts about particular options.

The book Managing Cover Crops Profitably (third edition) from the Sustainable Agriculture Research & Education Program (SARE), is the best book I know on the subject. You buy the book for $19 or download it as a free PDF from SARE.

See Harvey Ussery  Four Outstanding Cover Crops for Summer.

Cover Crops in Summer

 

Buckwheat seedlings. Buckwheat is our quickest easiest summer cover crop.
Photo Pam Dawling

Sow summer cover crops while it’s still too early sow your winter cover crops. Sow oats 5-8 weeks before your average first frost to get good size plants before they get winter-killed. Sow winter rye from 14 days before to 28 days after first fall frost. Oats, barley, wheat and rye sown too early can head up and seed before you get to winter, making them less useful. Instead, sow fast-growing summer cover crops in any space possible, for weed suppression and a boost to soil organic matter.

Keep live roots in the ground as much of the time as possible, to feed the microorganisms and anchor the soil, preventing erosion in heavy rains. Dead roots also have a role, providing drainage channels in the soil and letting air in deeper. Adding organic matter to the soil is a way of banking carbon, as well as providing nutrients for your crops.

Deep-rooted cover crops draw up nutrients, bringing them up where crop plants can access them. Leguminous cover crops provide nitrogen, saving imports of organic fertilizers or a big compost-making operation.

Iron and Clay southern peas flowering in September. Photo Pam Dawling

Advantages of Summer Cover Crops

Suppressing weeds. Weeds grow fast in summer, and fast-growing summer cover crops will suppress them. Sowing cover crops helps us stay on top of developing problems.

Growing biomass. Many summer cover crops can be mowed or scythed down (before flowering) to encourage regrowth. The cut biomass can be left in place, or raked out and used as mulch in another part of the garden. Some can even be used as feed or bedding for small livestock.

Feed the soil life. Cover crops are solar-power generators, transforming sunlight, water and carbon dioxide into leaves and roots. They also release carbohydrates and other nutrients that feed soil microbes, earthworms and other soil life forms that make soil fertile. This cycle of nutrients constantly passes through plants and back into the soil. When you aren’t growing vegetable crops, cover crops keep this cycle going.

Increasing biodiversity. Cover crops can attract beneficial insects, birds and amphibians to feed and reproduce. Biodiversity encourages ecological balance that can help reduce plant diseases and pest attacks.

No-Till summer cover crops. A mix of soybeans or southern peas and foxtail millet can be grown during the summer and mow-killed before planting in the fall. Garlic perhaps?

Overcoming the Challenges of Summer Cover Crops

Finding space. If you’ve been carefully filling every space with vegetables, you may think you have no room for cover crops, but because they feed the soil, it’s worth making space for them too. It’s part of the wholistic picture of sustainable food production. It’s worth making a priority to have one bed or one section of your garden in cover crops, because of what they can do for your soil.

  1. Have a goal of No Bare Soil. Seek out odd spaces to fill with cover crops.
  2. Use space beside rows of sprawly crops short-term. Undersow buckwheat in winter squash, watermelon or sweet potatoes, and mow or till as soon as the vines start to run.
  3. Take a cold hard look at aging crops: better than keeping an old row of beans to pick every last bean, is to pull up those beans and sow a quick cover crop. It will be a more valuable use of the space.
  4. Take a look at your planting plan. When is your next crop going in that space? Rather than till the soil to death to manage the weeds, use a cover crop. In the winter, see if you can re-arrange your crop rotation and planting plan to make more time windows of a month or more, with the plan of using more cover crops.
  5. Undersow growing crops with a cover crop when the vegetable crop has been in the ground for about a month. The food crop will be big enough to resist competition from the cover crop, and the cover crop will still get enough light to grow. This way fewer weeds grow, and your cover crop is already in place when the food crop is finished, giving it longer to reach a good size. We undersow our sweet corn with soybeans (soy and oats for the last sweet corn planting). Buckwheat can be under-sown in a spring vegetable crop, to take over after the food crop is finished. You can plant a short cover crop on the sides of a bed of any tall crop like tomatoes or pole beans. You will need to provide extra water, especially while the cover crop is germinating. Read my Mother Earth News post on undersowing in late summer and early fall.
  6. Sweet corn with undersown soy cover crop.
    Photo Kathryn Simmons

    You can also undersow winter cover crops during late summer and early fall to last over the winter and even the next year. We broadcast clover among our fall broccoli and cabbage with the plan of keeping it growing for the whole of the following year, mowing once a month to stop annual weeds seeding.

High temperatures. Most summer cover crop seeds will germinate just fine at high temperatures provided they get enough water.

Drought. If it doesn’t rain much in your summers, or your irrigation water is limited, choose cover crops that are drought-tolerant once germinated. After sowing, work the seed into the soil and roll or tamp the soil so that the seed is in good contact with the soil, which will help it get the water it needs rather than drying out in an air pocket. To get good germination, keep the soil surface visibly damp. You can use shadecloth, a light open straw or hay mulch, or even cardboard to reduce evaporation. Be sure to check every day and remove the cardboard as soon as you see the first seedlings.

Sowing small spaces. You can sow cover crops in rows by hand in very small spaces, or use an EarthWay seeder. Or you can broadcast: tuck a small bucket of seeds in one arm, take a handful of seeds and throw them up in front of yourself in a fanning movement, trying not to spread seed into neighboring beds where you don’t want them. Aim for about two seeds/sq in (1 sq inch is 6.5 sq cm, I’ll leave you to think what it looks like). Don’t sweat the details, you will get better with practice! This isn’t brain surgery! For more even coverage, try broadcasting half the seed walking up and down the length of the patch, then sow the other half while walking at 90 degrees to your original direction. Rake or till the seeds in, trying to cover most of the seeds with 0.5-1” (1-2.5 cm) of soil. Water with a hose wand or sprinkler to keep the soil damp until germination.

A bed ready for tilling after mowing the cover crop and spreading compost.
Photo Pam Dawling

Working with the time you have left.

  • If you have only 28 days until the patch is needed for a food crop, you can grow mustard or buckwheat. Or weeds, if you’re careful not to let them seed!
  • If you have at least 45 days, you can grow soy or Japanese millet.
  • If you have only 40-60 days before frost you can sow oats with soy beans or spring peas as a winter cover crop to winter-kill.
  • If you have 50–60 days until frost, or between crops, Browntop millet is possible. In the right climate, sunn hemp can mature in 60 days.
  • With 60–80 days until frost, or between one crop and the next, you could sow buckwheat, soy, southern peas, spring peas, German foxtail millet, pearl millet, Japanese millet, or sorghum-sudangrass to frost-kill. Or you could sow oats with Austrian winter peas, crimson clover, or red clover to grow into winter.
  • If you have longer than 80 days you can sow any of the warm weather cover crops now and then move on to winter cover crops 40 days before your frost. Or you could sow a fast-growing vegetable crop.

Five Easy Summer Cover Crops that Die with the Frost

Buckwheat

Buckwheat cover crop in flower.
Photo Pam Dawling

Buckwheat is the fastest and easiest cover crop, a 2’-3’ (60-90 cm) tall broadleaf annual that can be flowering within three weeks in very warm weather, 4 weeks in regular warm weather. Because it grows so fast, it quickly crowds out germinating weeds. Plant buckwheat after all spring frosts have passed, until 35 days before the fall frost at the latest.

If you have longer than 4 weeks for cover crops, you have the option of letting the buckwheat self-seed and regrow (only do this if you’ve finished growing vegetables for that year in that space). Another option if you are not close to the frost date is to incorporate the buckwheat in the soil and then sow fresh seed.

Buckwheat is very easy to incorporate into the soil. Use a mower or scythe to cut it down 7-10 days after it starts flowering, and then either let the dead plants die into a surface mulch and plant into that, or rake it up and compost it, or dig or till it into the soil. For small areas, you can simply pull up buckwheat by hand – this is what we do in our hoophouse.

Buckwheat can be used as a nurse crop for fall-planted, cold-tolerant crops, which can be difficult to germinate in hot weather. Sow a combination of buckwheat and a winter vegetable to shade and cool the soil. When frost kills the buckwheat, the vegetable crop can continue growing with no competition.

Buckwheat is not related to any of the common food crops, and so it is simple to include it in crop rotations.

See my post and article about buckwheat here.

Sorghum-Sudangrass

Sorghum-sudan cover crop after mowing to encourage regrowth.
Photo Kathryn Simmons

One of our favorite summer cover crops is sorghum-sudangrass, a hybrid that grow 5’-12’ (1.5-3.6 m) tall in 60-70 days and produces an impressive amount of biomass. You’ll need big machinery, at least a big BCS mower, to deal with sorghum-sudangrass. If you have only hand tools and a lawnmower, I recommend growing German foxtail or Japanese millet instead.

Plant sorghum-sudangrass about two weeks after your first sweet corn planting date and anytime onward until six weeks before frost. After it’s established, sorghum-sudangrass is highly drought-resistant and thrives in summer heat. Plant in rows 8” (20 cm) apart, with seeds 1’ (2.5 cm) deep, 1.5” (4 cm) apart. Sorghum-sudangrass will smother weed competition, and make big improvements to the soil texture and the levels of organic matter.

When the sorghum-sudangrass reaches 4’ (1.2 m) tall, cut it down to 1’ (30 cm) to encourage regrowth and more, deeper, roots growth that will loosen compacted soil. The cut tops make a good mulch, or you can leave them in place.

Sorghum-sudangrass roots exude allelopathic compounds that suppress damaging nematodes and inhibit small seeds (weeds and crops) from germinating and inhibits the growth of tomatoes, lettuce, and broccoli. Wait at least 6 weeks after killing sorghum-sudangrass before planting another crop in the same spot. Plant earlier at your own risk – I think we’ve had some success despite the warnings. Be careful if feeding to livestock. Read up about prussic acid poisoning from this cover crop.

Soybeans

Soybeans as a cover crop
Photo agcrops.osu.edu

These are a quick easy leguminous cover crop for warm weather. Buy organic seed if you don’t want GMOs, as almost all non-Organic soybeans in the US are GMOs. We plant these whenever we have a minimum of six weeks for them to grow before frost or before we’ll need to turn them under. They aren’t the highest N-producing legume, but they are very fast-growing and easy to manage.

Southern Peas

Iron and Clay southern peas as cover crop in the hoophouse.
Photo Pam Dawling

Also known as cowpeas, although I have heard this might be perceived as insulting by African-American families who use them as food. Southern peas grow fast (60-90 days), thrive in heat, and are very drought-tolerant. Their taproots can reach almost 8’ (2.4 m) deep. They grow well in almost any soil, except highly alkaline ones. Southern peas attract beneficial insects.

Sow southern peas 1-2 weeks after your sweet corn, when the soil has warmed up. You can continue sowing until 9 weeks before a killing fall frost. Sow seeds 2” (5 cm) apart, 1” (2.5 cm) deep in rows 6” (15 cm) apart (give vining types more like 15” (40 cm) between rows. Close planting is needed to shade out weeds.

Because they are fast-growing, southern peas can follow spring vegetable crops and fix nitrogen in time to feed heavy-feeding, fall-planted onions or garlic.

Sunn Hemp

Sunnhemp cover crop at Nourishing Acres Farm, NC.
Photo Pam Dawling

Sunn hemp is a nitrogen-fixing legume from the tropics, which can grow as much as 9’ (2 m) tall in just weeks. Sow sunn hemp from 1-2 weeks after your sweet corn sowing date, up to 9 weeks before a killing frost. It tolerates a wide range of soils (but not if waterlogged), and dies with the frost. Plant inoculated seed (use the same inoculant as for southern peas) 1” (2.5 cm) deep, with seeds 1.5” (4 cm) apart in the row, and with rows 6” (15 cm) apart. Sowing densely will smother the weeds.

If you sow in a summer gap between spring and fall vegetable crops, it will provide a nitrogen boost for the fall crop. In dense plantings, it can fix more than 120 lbs (54 kg) of nitrogen and 12 pounds of biomass per 100 sq ft (0.56 kg/sq m). 60 days after sowing, the stems thicken and become fibrous and high in cellulose; cutting at this stage produces long-lasting mulches that increase soil carbon. If you cut the crop back at a younger stage, this will stimulate branching (more biomass) and more root penetration (better drainage).

Late Summer Cover Crops for Winter: Oats and Barley

Occasionally our winter cover crop oats don’t get winter-killed. March photo by Pam Dawling

In late summer you can sow oats for a winter cover crop that will be killed at 6°F (-14°C). We sow in late August and early September in Zone 7. Inexpensive and easy to grow, oats are a standard fall cover crop: a quick-growing, non-spreading grass, oats will reliably die in Hardiness Zone 6 and colder, and nine years out of ten in zone 7.

Barley grows even faster than oats, and on average it will get killed later in the winter. It usually dies at 17°F (-8°C), making barley another choice for gardeners in regions where oats are used.

Cover Crop Resources

My book Sustainable Market Farming has a chapter on cover crops and 9 pages of charts about particular options.

The book Managing Cover Crops Profitably (third edition) from the Sustainable Agriculture Research & Education Program (SARE), is the best book I know on the subject. You buy the book for $19 or download it as a free PDF from SARE.

Buckwheat, a wonderful summer cover crop

Credit Southern Exposure Seed Exchange
Credit Southern Exposure Seed Exchange

The June/July issue of Growing for Market magazine has an article I wrote about buckwheat, one of our favorite summer cover crops.

Buckwheat is a fast-growing warm-season broadleaf annual that is a very useful cover crop. Its special strengths are in weed-suppression, attracting beneficial insects, improving the soil tilth (aggregate structure) with its fibrous roots, and extracting potassium, calcium and phosphorus from the soil to the benefit of following crops. Buckwheat is almost three times as good as barley in scavenging phosphorus, and more than ten times better than rye (a poor phosphorus scavenger). Buckwheat can do fairly well on poor soils, is tolerant of a range of soil pH and is an easy crop to deal with manually or with small-scale equipment. Because buckwheat is not related to any of the common food crops, it is simple to include in rotations.

There wasn’t space in the magazine to include all the great resources I found, so I’m including them here.

Resources in the article

e-Organic’s Buckwheat for Cover Cropping in Organic Farming

Principles of Sustainable Weed Management in Organic Cropping Systems

Virginia Association for Biological Farming Infosheet Seeders: Using Manually-operated Seeders for Precision Cover Crop Plantings by Mark Schonbeck and Ron Morse,

How to De-hull Buckwheat with the Country Living Mill

Buckwheat beginning to flower. Credit Southern Exposure Seed Exchange
Buckwheat beginning to flower. Credit Southern Exposure Seed Exchange

Buckwheat Resources

Cornell Buckwheat Cover Crop Handbook (thorough, but not organic) .

Buckwheat Cover Crop Guide – Jefferson Farm and Gardens

General Cover Crop Resources

 Agricultural Sustainability Institute at University of California Davis, Cover Crop Database

 USDA/ARS Cover Crop ChartThe crop “tiles” in the chart can be clicked to access more information about 46 cover crops.

NCSU Department of Horticultural Sciences Horticulture Information Leaflet 37, Summer Cover Crops,

SARE, Managing Cover Crops Profitably, the whole book is available as a free download

CEFS Organic Production: Cover Crops for Organic Farms, under Resources, Guides, Organic Production Guide:

Cornell University, Cover Crops for Vegetable Growers,

GFM-June July 2013-cover-300px

Twin Oaks Garden Task List for May

Turnips interplanted with radishes - two spring crops from one bed. Credit Kathryn Simmons
Turnips interplanted with radishes – two spring crops from one bed.
Credit Kathryn Simmons

During the Month:

Lettuce Factory: Sow heat-resistant lettuce outdoors, every 8 to 6 days, #10, 11, 12, 13, 14. Transplant 120/week (1/3 bed). #7, 8, 9, 10, 11 this month.

Deal with potato beetles with Spinosad [or Neem] once larvae are seen, if >50 adults/50 plants or >200 larvae/100 plants. Spinosad: Spray when bees not flying (early morning or late evening.) Shake well, 1-4 Tbsp/gall. Expect to need 1.5-2 hours and 9-10.5 galls. Clean and triple rinse the sprayer. Do not flush in creek or pond. Repeat if needed in 6-7 days – could spot spray where larvae are seen. Flame weed potatoes before 12” high, if needed.

Deal with asparagus beetles, if necessary. See notes under April.

Early May:

Flat of home-grown sweet potato slips. Credit Kathryn Simmons
Flat of home-grown sweet potato slips.
Credit Kathryn Simmons

Continue cutting sweet potato slips until we have enough.

Transplant when hardened off: celery, celeriac, lettuce #7, main tomatoes (2’).

Set out drip tape & bioplastic mulch , transplant Romas (2’),  peppers (18” when soil 70°F, dogwood blooms dropping), hot peppers, and melons #1, sweet potatoes

Sow peanuts (120d), asparagus beans in bed w/ celery, okra, sunflowers. limas #1, cow peas #1 (68d)

Roll out driptape and bioplastic mulch for watermelons.

Cover Crops: Sorghum-Sudan, soy, buckwheat, or pearl millet as summer cover crops, now frost is past.

Mid-month:

Plant sweet potatoes, 16″ apart, with 4-4.5′ between ridges, 5’ at edges of patch. Install drip irrigation on ridges and plant at every other emitter. Ideal if soil temp is 65°F for four consecutive days before planting.  If weather dry, dip roots in mud slurry before planting.  Plant 2-3” deep, with at least 2 nodes in ground, and at least 2 leaves above ground.  If slips are long, plant horizontally to increase production.

Transplant lettuce #8, eggplant (2’ apart, single row in center of bed, spray off flea beetles with jet of water & cover immediately), watermelon, insectaries, (okra if not direct-sown – mulch later, when soil warm).

Set out drip tape and biodegradable mulch and transplant melons and watermelons at four weeks old max. Cover for 3 weeks. Move rowcover off broccoli (12 pieces) and strawberries (~8 pieces) Watermelon needs 12 pieces.

In greenhouse sow tomatoes #3, filler watermelons & Romas. Sow cukes & squash #2 if spring is late and cold, and direct-sowing not wise.

Sow beans #2 (5/14, 28 days after #1), edamame #2, carrots #6, sunflowers.

Till between rows of corn #1 & transplant in gaps and/or thin to 8”.

A bed of various varieties of onions. Credit Kathryn Simmons
A bed of various varieties of onions.
Credit Kathryn Simmons

Weed onions 3 weeks before expected harvest date, and broccoli.

Garlic: Harvest garlic scapes, remove mulch from garlic, and weed.  Move mulch to weeded broccoli.

Check maturity of potato onions and garlic. Likely harvest order is fall potato onions 5/25-6/10, hardneck garlic 5/30-6/15, spring potato onions 6/3-6/18, bulb onions 6/11-6/30, softneck garlic 6/5-6/15.

#4 Spring Tractor Work mid-May – Disk areas for June potatoes, corn 3,4,5, & later succession plantings of beans, squash, cucumbers.

Late May:

Mow between no-till paste tomato rows before mulching with hay. Fill gaps, weed, tuck mulch.  Set up posts and string weave the tomatoes, using thick baler twine for lower 3 rows. Really try to keep up with weekly string-weaving.

String weave 1 row around peppers, using short stakes.

Clear empty coldframe and mulch with cardboard or plant something.

Till each corn twice, undersowing at 2nd tilling (30 days), when 12” high, with soy for #1-5, oats/soy for #6. Thin corn to 8”. Avoid cultivating corn after it’s knee-high—roots are shallow.

Sow corn #2, cowpeas #2; cukes #2 (picklers and slicers), summer squash & zukes #2 5/24 (or in greenhouse 5/14, transplant 6/7), watermelons #3, winter squash 5/26 (put woodash with seeds to deter squash vine borer). If squash sowing is late, don’t sow Tahitian butternut – slow.  Cover cucurbits (perhaps not winter squash) against cucumber beetles. Max. cuke beetle population is mid-May; keep susceptible plants well-covered until flowering.

Transplant lettuce #9, 10, 11; Roma paste tomato replacements for casualties, insectary flowers. Fill gaps in eggplant, peppers, melons, watermelons.

Store any seeds not needed until fall or next spring, in basement (radishes, onions, winter squash, watermelon).

Harvest fall planted Potato Onions in dry weather, after tops have fallen, (5/25-6/10, spring planted 6/3-18).  May not all be ready at once. Handle gently. Dry as clusters in barn on wooden racks for 1-2 months, using fans. Service fans or buy new as needed. Eat potato onions >2.5” without curing, unless yield is very low, in which case label & refrigerate, then plant in September. Weight after drying for 1 week is approximately twice the final weight. First sorting is late June. Use the Worksheet and Log Book

Hanging garlic in vertical netting. Credit Marilyn Rayne Squier
Hanging garlic in vertical netting.
Credit Marilyn Rayne Squier

Harvest garlic when 6th leaf down is starting to brown on 50% of the crop (ie .5 green leaves, so that 5 skins cover cloves), or cut open horizontally- when air space is visible between. stem and cloves it’s time to harvest.  [Could replant small cloves immediately for garlic scallions.] Allow 15 mins/bucket harvesting and 15 mins/bucket for hanging in netting in barn,.

Till garlic area, sow soy & buckwheat to control weeds until fall carrot planting.

Plan fall and winter crops for raised beds.

Cover crops: can sow buckwheat, soy, millet, and sorghum-sudan during May.

Perennials: Put up blueberry netting before fruit sets. Weed & water & top up mulch. Mow grape & fall raspberry aisles. New grapevines: remove side branches and fruitlets. Weekly: visit grapes and log progress 4/20-5/30. If asparagus weeds are getting out of hand, mow down one or more rows to keep control.

Our Concord grapes in late May. Credit Bridget Aleshire
Our Concord grapes in late May.
Credit Bridget Aleshire

Harvest: Asparagus, hoophouse beans, beets, beet greens, broccoli, cabbage, first carrots, chard, collards, garlic scallions, garlic scapes, kale, kohlrabi, lettuce, peas, radishes, rhubarb, scallions, senposai, spinach, hoophouse squash, strawberries, turnips, hoophouse zucchini. (Clear spinach, senposai, collards, kale, probably in that order)DSC03323