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.

Growing Great Sweet Corn

Silver Queen sweet corn almost ready to harvest.
Photo Kathryn Simmons

I wrote about success with planting sweet corn in May. here are tips for continuing success as your corn grows!

Caring for the Sweet Corn Crop

Generally, corn needs cultivating (hoeing and weeding) at least twice, once two weeks after sowing, and once at four weeks. Even better are four cultivations: one at 7 days, a second at 14, a third around 21 days (when the plants are 6-12” (15-30cm) tall) and finally one around 35 days when they are 18-20” (45-50cm) high. We use a walk-behind tiller, and follow up with hoeing and thinning. A wheel hoe can be a useful tool. After about 30 days, corn plants get too big to get machinery between the rows.

Another good resource is ATTRA Sweet Corn: Organic Production.

At tight spacing, adequate irrigation becomes more important. Never allow soil in corn plantings to dry out. More than 1” (2.5cm) per week may be needed for maximum productivity, although corn is more drought tolerant than some crops. The most important times for watering are silking (when the silks first become visible outside the husks) and ear-filling.

There used to be a belief that it helped production to remove the suckers that came from the base of the plant. This idea has been tested, and that practice has been found to damage plants and possibly even reduce yields. (Reports from Clemson in 2002 and Colorado State in 2004).

Flame-weeding can be used after planting, pre-emergence, or, with care, after the crop is 2” (5cm) tall, using a directed flame. Consult ATTRA Flame Weeding for Vegetable Crops

Sweet corn undersown with soybeans as a cover crop. We often use soybeans as a traffic-tolerant, nitrogen-producing cover crop that also deters weeds.
Photo Kathryn Simmons

Undersowing Sweet Corn

No-till planting into strips tilled in a white clover living mulch sounds good but has been found tricky, especially during the grower’s learning curve. Jeanine Davis addresses this in NCSU’s Organic Sweet Corn Production. The clover may out-compete the corn, becoming invasive and hard to get rid of. Soil temperatures will be lower (a disadvantage in spring) and slugs and rodents may abound.

More successful is sowing a cover crop into the corn at the last cultivation, 28-35 days after emergence. We undersow with soybeans (oats and soybeans for our last planting). Although they don’t supply the highest amount of nitrogen, compared to other legumes, they are cheap, quick, somewhat shade tolerant and can withstand the foot traffic during harvesting. Other growers sow forage brassicas. Research has shown that this does not depress corn yields. The brassicas can be harvested for forage after the sweet corn harvest is finished. Undersowing with white clover is also possible.

Succession Planting of Sweet Corn

In order to have a continuous supply of sweet corn all summer, a bit of planning and record-keeping is called for so that each year’s plan can be fine-tuned. The easy and approximate method of getting a good supply is to sow more corn when the previous sowing has 3-4 leaves, or is 1-2” (2.5-5cm) tall. That will be about every two weeks. For a more even supply, sow several different varieties, with differing days to maturity, on the same date. We sow Bodacious (77 days), Kandy Korn (89 days) and Silver Queen (96 days) on the same day, and get over two weeks of harvests.

For fine-tuning for the most even supply, nothing beats real information about what happened, written at the time it happened. We have a Planting Schedule on a clipboard in the shed, and we write down actual sowing dates (next to the planned sowing date), and harvest start and finish dates. Having graphs of sowing and harvest dates for each crop has been very useful for planning effective planting dates. Use the Succession Planting method to calculate best planting dates and intervals for a continuous supply. We make six plantings: 4/26, 5/19, 6/6, 6/24, 7/7 and 7/16, to provide fresh eating every two weeks. The planting intervals are 23, 18, 18, 13, and 9 days. Because we plant three varieties, new corn comes in three times during each two weeks.

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.

Our sixth (and last) sweet corn planting showing our three-variety sequence. From the right: Bodacious, Kandy Korn and Silver Queen.
Photo Kathryn Simmons

Fast-Maturing Sweet Corn Varieties

Early Maturing Sh2 Varieties: The Supersweet corn varieties are where most of the attention goes these days, and bicolor is preferred. In order of maturity (speediness in ripening): Catalyst XR (bicolor, 66days); Sweetness synergistic (bicolor, 68d); Kickoff XR (bicolor, 69d); Temptress synergistic (bicolor, 70d); Xtra-Tender 2171 (bicolor, 71 d); Nicole (white, 72d); Xtra-tender 20173 (bicolor, 73d); Signature XR (bicolor, 73d); Anthem XR (bicolor, 74d); Natural Sweet Organic (bicolor, 74d); Xtra-tender  3473 (white, 75d); SS2742 (Bicolor, 75d)

Early Maturing SU Varieties: Among yellow SU cultivars, Earlivee is the earliest to mature, at 58 days, and Seneca Horizon matures in 65 days. Sugar Pearl at 73d  is the earliest white cultivar to mature. Quickie, at 64 days, Double Standard (OP, 73d) and Butter and Sugar at 73 d, are the earliest bicolor cultivars to mature.

Early Maturing SE Varieties: Among yellow SE varieties, Precocious and Spring Treat mature earliest, at 66 and 67 days, respectively. Bodacious (yellow, 75d) is well worth the wait! Of white varieties, Spring Snow, at 65 days, is the earliest to mature. There are no bicolor SE varieties.

Early maturing SE+ varieties: Sugar Buns (yellow, 70 days); Trinity (bicolor, 68d)

Remember, if you decide to grow several kinds, not to mix sh2 kinds with anything else, or everything will taste starchy.

Sweet Corn Season Extension

Transplanting can provide an earlier harvest, as already mentioned. Clear plastic mulch is sometimes used to increase soil temperature and germination rate, and to conserve moisture, producing earlier maturing corn. The plastic is spread over the seeded beds and slit when the seedlings emerge. It can be cut and removed 30 days after emergence. Weed-free seed beds are needed for this method to work organically, and plastics disposal is an issue. Rowcover is another way to warm soils (and keep birds off).

Our second sweet corn planting on July 8, a few weeks away from harvest.
Photo Pam Dawling

Pests and Diseases of Sweet Corn

Crows and other birds can be troublesome, removing the seed before it even grows. We leave the row-marking ropes in place (when hand sowing), or put some sticks and string in after machine sowing. Bird-scaring flash-tape may be even more effective. Rowcover would also work.

Some say interplanting corn with big vining squashes deters raccoons and other critters, but I think it deters crew too!

There are several caterpillar pests. An integrated organic approach to keeping pest numbers below economically damaging levels includes crop rotations, tillage, choosing resistant or tolerant varieties, encouraging beneficial insects, and ensuring adequate fertility and water. The next step is to scout for pests regularly, and take action as required.

Corn Ear Worm (CEW) is the most common pest. There may be six generations a year in the South. These caterpillars can bite – it’s just a nip, but can be a shock! A first line of defense is to choose varieties with tighter husks, which are harder for the worms to get into (Bodacious, Tuxedo, Silver Queen). Natural predators can be encouraged by planting alyssum or other small, open-flowered plants. You could buy Trichogramma wasps. The Zea-later was a tool developed for applying vegetable oil in the tip of each ear, mixed with Bt, 2-3 days past the full-brush stage of silking. Unfortunately  the treatment caused pollination problems and so it has fallen out of use. If pest numbers are not too high, you can simply cut or snap the ends off the ears.

Corn Earworm larvae come in many different colors. And they can bite!
(Photo: J. Obermeyer Purdue Extension)

European Corn Borer (ECB) drills through the whorl of leaves of the young plants, leaving a pattern of large holes as the plant develops. Bt and Spinosad will kill these, as will Trichogramma wasps. To reduce damage in future years, be sure to mow and disk old corn stalks into the soil at the first opportunity. Organically farmed soils have less of a problem with ECB.

Fall Army Worms (FAW) are also killed by Bt and Spinosad. These three pests (CEW, ECB, FAW) can be monitored in a single program, starting when the corn plants are at the whorl stage. At that point, scout for FAW, and treat if more than 15% of your plants are infested. At the pre-tassel and tassel stage scout for ECB and FAW. If infestation exceeds 15%, make a foliar spray with Bt or Spinosad. Check again in a week and repeat if needed. Then at the early silk stage, look for CEW and if needed, inject oil in the tips. If you also see ECB moths, apply Bt or Spinosad.

Cutworm can be a problem following sod, or if there are adjacent grassy areas. Bait them with bran, cornmeal or hardwood sawdust mixed with molasses and water – these baits swell inside the pests and kill them.

Corn Rootworms are best controlled by rigorous rotations.

For a more complete description of corn insect pests, see the 2004 Organic Insect Management in Sweet Corn by Ruth Hazzard & Pam Westgate. It includes good photos of the beasties. Cornell has a good Resource Guide for Organic Pest and Disease Management. Search under Crop Management Practices for Sweet Corn.  Be aware of the updated info on the pollination issues with applying oil in the ear tips, since these publications came out.

Corn Smut fungus (Ustilago maydis), known in Mexico as Huitlacoche, is edible at the stage when the galls are firm and tender. The flavor is sweetish. Silver Queen is the variety “best” at producing this fungus, should you wish to grow it. We carefully harvest the infected ears (or pieces of stem) into a special Smut Bucket, trying not to scatter the spores. Because none of us like this delicacy, we take it to the compost pile.

Young sweet corn plants in July (our fourth planting). And solar panels.
Photo Bridget Aleshire

Sweet Corn Harvest

Harvest corn 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.

Some of this information comes from my book, Sustainable Market Farming.

Plentiful harvest of sweet corn and tomatoes.
Photo Twin Oaks Community

Dealing with weeds

 

Galinsoga- a fast-growing, fast-seeding weed of cultivated soil. Photo Wren Vile

Dealing with weeds

Why take action against weeds?

Weeds compete with crops for sunlight, water and nutrients, and can encourage fungal diseases by reducing airflow. Too-frequent cultivation to remove weeds can leave the soil more prone to erosion. Each tilling or deep hoeing stirs air into the soil and speeds combustion of organic matter. Most weeds respond well to nutrients, especially nitrogen. If you give corn too much nitrogen, even as compost, its productivity will max out and the weeds will use the remaining nutrients.

Remove weeds at their most vulnerable stage, or at the last minute before the seedpods explode —ignore weeds doing little damage.

Types of Weeds

  •   Annuals and perennials;
  • Stationary perennials (docks) and invasive perennials (Bermuda grass);
  • Cool-weather and warm-weather types;
  •  Quick-maturing and slow-maturing types;
  •   “Big Bang” types (pigweed) versus “Dribblers” (galinsoga).
Burdock is a large perennial weed with a huge root. Photo Bridget Aleshire

Sustainable Weed Management

1.      Prevent weeds from germinating

  •  Grow vigorous crops adapted to the locality,
  •  Switch between spring and summer crops in rotation,
  •  Mulch or tarp to bury short-lived weed seeds
  • Plant promptly after cultivation, so weeds don’t get the head start,
  • Transplant rather than direct sowing, giving your crop a head start on the weeds,
  • Use close spacings, leaving less space for weeds,
  • Use drip irrigation rather than sprinklers, discouraging weed germination between the rows,
  •  Plant cover crops, including no-till systems,
  • Reduce tillage whenever you can, for example, by relay planting, where the new crop is planted while the previous crop is still in place, and prevent new weed seeds coming up to the surface.
Remove weeds before they set seed. Thistle seeds blow a long way on the wind.
Photo Wren Vile

2.      Reduce weed seeding

  • Practice timely cultivation, mowing, flaming, grazing by cattle, chickens, ducks, geese. As Margaret Roach says: “No matter what weed you are facing, if it’s flowering or setting seed now, be sure to behead it: mow it down, harvest the blooms for bouquets, or otherwise prevent a successful sexual reproduction cycle.”
  • Reduce weed seed banks to 5% of original levels by preventing weeds from seeding for 5 consecutive years.
  •  Use post-emergence organic weed killers: corn gluten, vinegar, flaming
Dandelions are another perennial weed with seeds that blow and spread easily. Photo Wren Vile

3.      Reduce weed seed viability

  •  Reckon that most weed emergence happens within two years of the seeds being shed.
  •  Encourage seed-eating birds, insects, worms, mice
  •  Small, short-lived seeds of weeds with no dormancy period, such as galinsoga, will almost all die within a year or two if they are buried a few inches. Till and mulch to bury short-lived weed seeds.
  •  Longer-lived seeds (pigweed, lambsquarters, velvetleaf) if buried, may remain viable and dormant for years – Leave such weed seeds on the soil surface, rather than tilling them in! Delaying tillage if weeds have already seeded generally reduces the number of seeds added to the long-term seed bank. Seeds lying on or near the soil surface are more likely to deteriorate or become food for seed predators than buried seeds,
  •  If they do not get eaten, dry out or rot, seeds on top of the soil are more likely to germinate than buried seeds, and you can take prompt action.
  • Use stale seed-beds – prepare bed a couple of weeks before planting, water as if you had planted. The day before planting your crop, hoe the surface shallowly to kill new weeds,
  •  Solarize weedy soil in hot weather to kill weed seeds – mow the weeds, cover the soil tightly with clear plastic, weighted down or dug in round the edges. Bryan O’Hara in No-Till Intensive Vegetable Culture has popularized this technique, which makes a great use for used hoophouse plastic film. Solarizing can produce temperatures of 125˚F (50˚C) whereas temperatures under tarps (see section on perennial weeds) will be more like 110˚F (43˚C). You may need only 1-3 sunny days to kill crop residues with solarization. Cover crops and weeds may take longer to die. The heat will not go deep into the soil in that short time, and so more of the soil life will survive than with tarping.
Solarizing with clear plastic. Photo Pam Dawling

4.      Reduce the strength of perennial weed roots and rhizomes

  • Understand apical dominance: when a rhizome grows a green shoot, chemicals from that shoot prevent other nearby nodes on the same rhizome from sending up shoots.
  •  Act in a timely way – On long rhizomes, after a certain length, the dominance effect is too weak and another node can grow a shoot.
  •  Reduce the strength of perennial weed roots and rhizomes by frequent tilling or digging out.
  • Beware tilling invasive “traveling” perennial weeds once and thinking you’re done – When rhizomes are cut into pieces during tillage, the apical dominance is lost and each piece can grow a shoot of its own.
  •  Consider tarping: after tarping the plot for two summer weeks, 3-4 weeks in spring and fall, and two months or more in winter, dig out or pull up all the weed roots still alive.
  •  Next comes a counter-intuitive move (from Jesse Frost ): sow or transplant an intensive valuable crop in the areas with the worst perennial weed pressure. Of course this will motivate you to deal effectively with the weeds!
  • Pull out the pieces to dry on the surface – the depleted pieces of root or rhizome may die
  •  Or cultivate again when the new shoots have reduced the plant’s reserves (in the roots), but before they have grown enough to send energy back to the roots – it’s more effective than going almost daily after every sprig. Removing the shoots whenever the weeds reach the three- to four-leaf stage can be most effective.
  •  Late summer and fall turn out to be the best time for getting the upper hand over a wide range of common weeds, including Japanese knotweed, ragweed, Ailanthus, bindweed, curly dock and more. See Some weeds are best tackled late summer and fall Margaret Roach in A Way to Garden

Biointensive Integrated Pest Management

The weed strategies above follow the four steps of IPM: prevention, avoidance, monitoring and suppression.

1.      Prevention: Focus on restoring and enhancing natural balance and resilience to create healthy plants and soil, better able to withstand attacks. Maintain soil fertility, good drainage and soil structure; plant resistant, pest-tolerant, regionally adapted varieties; grow strong plants; practice good sanitation,

Hoe the small weeds in this bed of young lettuce soon, and the closing canopy of the lettuce will shade out most weeds after that. Photo Bridget Aleshire

2.      Avoidance: The next stage includes actions to reduce the chances of a weeds taking over. These actions are also known as physical controls. Physically remove weeds. Use good crop rotations, remove weed habitat, deter weeds. Provide habitat for weed seed predators.

3.      Monitoring:  regularly inspect your crops, find out when conditions are right for an outbreak of particular weeds. Be prepared. Identify your weeds and choose good strategies for each type. Decide when it is time to act. How to identify your weeds – online guides

4.      Suppression: When the prevention and avoidance strategies have been exhausted, control measures can be used to reduce damage of crops, while minimizing environmental risks. There are four types of sustainable bio-intensive control measures to choose from, starting with the least damaging to the wider environment:

  • a)      Biological control involves working to boost populations of existing resident weed seed predators. (For a few serious weed pests, like prickly pear, host-specific insect enemies are introduced)
  • b)      Microbial controls (bioherbicides) are plant-pathogenic fungi, bacteria, and viruses to kill weeds. Not common.
  • c)      Botanical control uses plant-based products for pest control. Examples include orange, clove and peppermint oils, and phytotoxic plant residues, such as root exudates from winter rye cover crops, and hay from sorghum, which inhibit germination of small seeds.
  • d)      Biorational controls (aka inorganic, mineral, controls) make use of manufactured products such as herbicidal soaps or strong vinegar.
Hoe weeds while they are small and you can be rid of those with short-lived seeds in a few years. Galinsoga and Outredgeous lettuce. Photo Pam Dawling

Critical weed-free period

One important factor is to observe the critical period of weed control for each crop. This is the period when crops are most affected by competition, whether from weeds, sister seedlings or those of an intercrop. Seedlings suffer more than transplants from being out-shaded. Transplants are soon past their critical weed-free period, perhaps half of it before you even set them out. As well as the critical period, take note of the severity of drop in yield for the particular crop. A lot of the information below comes from The Living Soil Handbook by Jesse Frost, which I had the pleasure of reviewing recently.

  • Small salad crops like arugula, spinach and baby lettuce mix, really need to be weed-free throughout their growth. Apart from the risk of being smothered and producing poorly, there is the risk of including bits of recognizable weeds in your salads.
  • Bulb onions also benefit from being weed-free throughout growth. Like other narrow-leaved plants, they are poor competitors. Carrots also are very poor competitors – for most of us, the over-abundance of carrot seedlings in the row are as much of a threat as the weeds. Parsnips are similar, with the added challenge that they are slow to emerge.
  • Peas do best with no competition, although, because they grow vertically, they can do OK with a companion crop such as spinach (or weeds!) a short distance away.
    Hilling potatoes before the weeds get too big will deal with the weeds as well as giving the potatoes more growing space. Photo Wren Vile

    Potatoes, weeds and standing water. Until the soil drains, the potatoes cannot be hilled, and the weeds here are already large. The yield will be reduced by weeds competing with the potatoes.  Photo Bridget Aleshire
  • Potatoes need 1-8 weeks after emergence free from weeds, although small weeds are not a problem and the process of hilling potatoes (needed to provide growing space) effectively deals with weeds.
  • Beets need 2-3 weeks after emergence weed-free from direct-sowing. My experience is that beets are their own worst enemy, and the clusters of seedlings that emerge from each seed-ball should be singled as soon as possible. Yields can easily drop 1-5% with small-average weeds. Turnips also need to be competition-free for the first few weeks after emergence.
  • Broccoli, cabbage, cauliflower, collards, kale and most Asian greens need 2-3 weeks after transplanting free of weeds.
  • Sweet potatoes need 2-6 weeks free of competition after planting. Because it gets hard to wade in and pull weeds later, we try to keep them weed-free.
Garlic beds under a stormy sky. Keep alliums free of weeds.
Photo Wren Vile
  • Garlic needs 3-7 weeks from emergence free of weeds. If you plant in the fall, start counting in early spring when weeds start to grow again. Like most alliums, the narrow vertical leaves make it a weak competitor.
  • Basil, cucumbers, squash, zucchini, lettuce and many other crops need four weeks from transplanting free of weeds. Be careful not to damage squash roots when removing weeds.
  •  Tomatoes need 5-6 weeks after transplanting free from competition, although they are fairly strong competitors later, and we routinely transplant our hoophouse tomatoes down the center of a bed of salad greens, progressively harvesting the greens over the next month. We have noticed problems only if we leave other crops too close for too long. Always prioritize the well-being of the new crop!
  • Peppers need 5-10 weeks after transplanting free from competition, although the drop in yield is small (5%)
  •  Fava beans need four weeks from emergence free of weeds
  •  Direct sown kale needs 6 weeks from emergence weed-free.
  • Okra requires 6-8 weeks after sowing weed-free. If you transplant okra as we do, half that period will be over by transplanting date.
  • Beans are a crop that can generally out-compete weeds (losing only 3% yield from competition), but keeping the rows clean until the beans flower (about 6 weeks from sowing) will maximize yields.
  • Corn needs about 7 weeks from seeding free of weeds (until there are 6 leaves).
  • Eggplant calls for 8 weeks from transplanting free of competition.
  •  Leeks, another weakly competitive allium, need 12 weeks post emergence weed-free. If, like us, you transplant leeks at about 10 weeks after sowing, this translates to hoeing the beds of transplanted leeks a couple of weeks of transplanting.

Flameweeding

I won’t say more about this here. Click the link to read previous posts.

Mulches

Mulches are a big asset in weed control. Organic mulches also add biomass to the soil. Remember not to use organic mulches around warm weather crops for their first month, as they need warm soil to grow well, and insulating mulches keep the soil cold.

See our experience with Biodegradable plastic mulch

Read Organic Farming Has A Plastic Problem. One Solution Is Controversial about the controversy surrounding biodegradable plastic in Organic Farming

Cover crops

Summer cover crops smother emerging weeds, prevent weed seed germination, between a spring food crop and a summer or fall one. Winter cover crops smother emerging winter annual weeds. Good cover crops for this purpose: sorghum-sudangrass, pearl millet, winter rye, wheat, barley, oats, buckwheat, brassicas (beware – rotation, bugs), lupins, red clover, subterranean clover, berseem clover, soybeans, cowpeas.

Ida Gold mustard (Sinapis alba) contains a gluscosinolate, ‘sinalbin’, a non-volatile compound that has shown the ability to inhibit weed seed germination. Tillage radish has a similar effect. The cover crop needs to be mowed and tilled in. Solarization after incorporating mustard is known as biofumigation.

Cover crops also improve the soil for crop production.

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

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.

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.

 

Workhorse Crops for May

Young bush bean plants.
Photo Pam Dawling

Workhorse Crops for May

Workhorses crops are reliable under a wide range of conditions, including weather, soil, date and other variables. Some are easy to grow, some pump out lots of food, some are “insurance crops” like chard that stand in your garden until you need to harvest them, some are especially profitable (for those growing for market).

I’ve chosen 14 crops (including two pairs) to focus on in the next 12 months, ending April 2022: Asparagus, beans, cabbage, carrots, chard, garlic, kale and collards, potatoes, sweet corn, sweet potatoes, tomatoes, watermelons, winter squash, zucchini and summer squash.

My motivation for this series is to help all who want to be more efficient, productive and profitable (if selling) as other parts of our lives expand again.

Workhorse Crops to Plant in May

May is a busy planting month here in central Virginia and probably most places in the northern hemisphere. Ten of our 14 Workhorse Crops can be planted once frosts are behind us.

Beans: We grow bush beans because we don’t like putting up trellises. In the past we had uncontrolled Mexican Bean Beetles that destroyed slower-to-mature pole beans. We found we could get crops of bush beans faster and sow them every few weeks or so to get a good supply of presentable beans every couple of days. 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. See my phenology post for information on when it’s warm enough to start sowing beans (and other crops) where you are.

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!

Multicolored chard. Wren Vile

Chard: A great insurance crop – it provides leafy greens when 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). We use chard for fresh greens in summer, when kale, collards, broccoli and cabbage from the spring have long gone. Because we don’t need chard until late May, we don’t sow until late March. We transplant in late April, into a hay mulch. This crop will be in the ground until mid-winter, and mulch will keep back most of the weeds. You could, of course, sow chard earlier if you want to eat it earlier. We also grow chard through the winter in our hoophouse, where it feeds us during the Hungry Gap.

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. You can plant at any date in between, so long as you have 80 days until your first frost. If time is a bit short, choose a fast-maturing variety (or be satisfied with small potatoes that won’t store).

Sweet corn: we make 6 sowings of sweet corn, to harvest from July 4 to mid-October. Start planting sweet corn when the leaves of the white oak are as big as squirrel’s ears. Click the link to check our planting dates, and to read about our first sowing of the year, catching raccoons and skunks, avoiding mixing types of corn and to view my slide show on succession planting. There’s a confusing aspect of hybrid corn varieties: if you plant a mixture of different genotypes, it can lead to starchy unpleasant-flavored corn. Also don’t plant Indian corn, popcorn or any kind of flint or dent corn within 600′ (180 m) of your sweet corn. For this reason we grow only sweet corn in our garden.

Our first sweet corn of the season.
Photo Pam Dawling

Sweet potatoes: I wrote about planting sweet potatoes in 2020. Modern varieties of sweet potatoes grow to a good size in as little as 90 days, so they are not just for the South! The further north you are, the longer the daylight at midsummer and the more photosynthesizing the plants can do. I have known people grow sweet potatoes in hoophouses if their climate isn’t warm enough outdoors. This can fit with winter use of the hoophouse for greens and roots. My book Sustainable Market Farming contains a whole chapter on this crop, including growing your own slips, but it’s too late to start that this year. Wait for the soil to warm before planting out your sweet potato slips. We plant ours a couple of weeks after the last frost, around the time we transplant peppers and okra.

Tomatoes: We plant out our main crop at the very beginning of May, unless the weather is too cold. To my surprise, I find I haven’t written much about transplanting tomatoes outdoors. 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. Outdoors, 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 later in the year.

Watermelon transplants in a Winstrip plug flat. Watermelons give earlier harvests from transplants, and plants in plug flats transplant easier then from open flats.
Photo Pam Dawling

Watermelons: Watermelon growing isn’t easy, but the rewards are so wonderful, that I gave watermelon a “Circus Pony” place among the workhorses! We transplant our watermelons, to get ripe ones as early as possible. Melons are tricky to transplant, as the roots don’t do well if disturbed. We have successfully used soil blocks, and these days we use Winstrip 50-cell trays. 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!

It’s important to keep the little seedlings in the greenhouse warm and in very good light, and away from drafts. Be careful not to overwater. They can keel over very quickly and once the stem collapses, remove that seedling before others die too. The goal is short stems!

When you transplant, get the start out of the flat and into the ground as quickly as possible with as little root damage as you can manage. This is not a crop where one person plops the plants out down the bed and someone follows planting them! Make the hole in the soil (through the plastic if you’re using that), by wiggling the trowel from side to side. Don’t dig a hole as if you are in a sand box, with a spoil heap at the side. Just form a space the right depth to get the whole of the stem in the ground.

Next gently pop the transplant out of the flat, perhaps using a table knife down the side of the cell. Push up from underneath. If all goes well, you’ll have the plant in a little block of soil (yes, like a soil block). Slide the transplant into the hole. You want all the leaves above ground, all the roots and stem in the ground. If the hole is too deep, lift the transplant carefully and scrape some soil into the hole. You don’t want to end up with the plant in a dip, as this can rot the stem. If the hole is not deep enough, you can to some extent hill up soil around the stem to protect it. You don’t want any of that fragile stem visible!

Water the day before, and one hour before transplanting, to help the soil hold together, and so that the plant has some reserves of water to see it through the initial shock of being set out. As you are transplanting, pause and water newly set plants every 20 minutes or so. Afterwards, water the whole planting and repeat on the 2nd, 3rd, 5th, 7th days and once a week after that.

Winter squash: By contrast, winter squash are very easy, and they store for months at room temperature. A true workhorse. We direct sow at the end of May, with the goal of harvesting in September and October, the last ones making Halloween lanterns. Soil should be at least 60°F (15.5°C), and all danger of frost should be past.

Young squash plant.
Pam Dawling

We have grown about 400ft (120 m) for 100 people, and mostly focus on Butternuts, Moschata types that grow best where we are and store longest. This is the type to focus on if you want trouble-free 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). As well as Waltham Butternuts, we include the large Cheese pumpkin, the long-storing Seminole, and the gigantic Tahitian Butternut. We also grow a couple of Maxima squashes which store quite well:  Cha-cha kabocha, and the large blue Jarrahdale, which have relatively high resistance to squash bugs compared to others in this group. Red Kuri, Festival (sweet dumpling type) and the New England Pie pumpkin are Pepo squashes, suitable for storing a few weeks only. (Pumpkins are squashes.) We grow some of these because they are sooner to harvest. Really they are more of a fall squash than a winter squash.

Winter squash do need a lot of space for each plant. This can mean a lot of hoeing until the vines spread, or mulch. Some can take 90-120 days to reach maturity, so plan carefully to be sure of getting a harvest. For dryland farming, without irrigation, it is important not to move the vines to new positions: the dew and rain drips from the leaf edges encourage root growth directly below the vines (where they get the most water and shade).

Sow 0.5”-1” (1-2 cm) deep. Either “station sow” 2 or 3 seeds at the desired final spacing, or make a drill and sow seeds 6” (15 cm) apart. There are various stick planters and jab planters that can be used for this kind of station sowing. Thin later. Rows will need to be 6’ (1.8 m) apart, or more. 9’ (2.7 m) between rows for the vining ones. Some growers plant in a square pattern so that spaces between rows can be mechanically cultivated in both directions. Bush varieties take less space than the vining types, and rows can be 4’ (1.2 m) apart.

You can transplant winter squash if you need to. We did this one year after our fields flooded. We started seeds in cell packs a week before our usual sowing date of 5/25. It worked just fine.

Summer squash plants under insect netting.
Pam Dawling

Zucchini (courgettes) and summer squash: Zucchini is a subset of summer squash. These are easy to grow, fast to produce warm weather crops. We make a succession of five or six plantings each year, so that we can harvest every day. Each sowing is half a yellow squash (Zephyr, Gentry) and half a 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 enough to direct sow – 60°F (15.5°C).

After transplanting or sowing, we hoop and cover the row with insect netting (rowcover also 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). At that point 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.

Zucchini and summer squash are another crop type that we succession sow, to get a continuous supply. More about succession planting another time. The time from sowing to harvest is only around 50 days.

Workhorse Crops to Harvest in May

Asparagus photo by Kathryn Simmons

Asparagus can be harvested if you have a patch. If not start to prepare a patch to plant out one-year crowns next early spring. Remove all perennial weeds while growing a series of cover crops. If you have asparagus, you probably know to snap off at ground level all the spears above a certain length. We chose 7” (18 cm). Do this every day for the 8-week harvest period. Daily harvest will also remove asparagus beetle eggs, controlling the pest level.

A bed of Early Jersey Wakefield cabbage in mid-May.
Photo Pam Dawling

Cabbage can be ready from late May, if you made an early sowing of fast-maturing varieties. Farao or Early Jersey Wakefield can take only 60 days.

Carrots can be ready from late May, if you sowed some in mid-late February

Chard is ready for harvest from late May (earlier if sown earlier), see above.

Harvesting garlic scapes in May
Photo by Wren Vile

Garlic scapes appear in hardneck garlic plants. Here it is also an indicator that our garlic will be ready to harvest in three weeks.

Kale and collards can be harvested until they are bolting, as long as the flavor is acceptable. Read more about bolting here.

Zucchini and summer squash from mid-May,

From storage: carrots, potatoes, sweet potatoes, winter squash

Workhorse Crops Special Topic: Deciding Which Vegetable Crops to Grow

Here’s a slideshow to help you decide which crops to grow. Some of the points are for commercial growers, some apply to anyone growing vegetable crops.

Deciding Which Vegetable Crops to Grow, Pam Dawling

Vegetable Seed Germination Temperatures and Phenology

Summer Lettuce Nursery Seedbed with Concept, De Morges Braun, New Red Fire and Loma lettuces.
Photo Bridget Aleshire. Lettuces are impossible to germinate if the soil is too hot. We use shadecloth (folded over on the right), a soil thermometer and ice cubes.

Vegetable Seed Germination Temperatures

Here is a table of vegetable seed germination temperatures. These apply to soil temperatures when you sow directly in the ground, and to air temperatures when you sow indoors in small containers. If your indoor air temperature is not warm enough when you want to sow your chosen crop (watermelons, anyone?) you can make a small warm place, or use a professional heat mat, or, for a small scale, germinate seeds in an instant pot! If you have one of these handy cooking devices, check the lowest setting. Perhaps labeled for making yogurt, it might be 91°F (33°C). Look at my chart below and see if your seeds will germinate at that temperature. You’ll have to experiment for the seeds which germinate well at 86°F (30°C) but not at 95°F (35°C). Don’t try this with spinach or lettuce! You might be surprised to see that some cool weather crops, like broccoli and cabbage, can germinate just fine at high temperatures!

You can see my chart is a work in progress, so if you can add any info, please leave a comment on this post. Bold type indicates the best temperature for that vegetable seed. The numbers indicate how many days it takes that seed to germinate at the temperature at the head of the column. Where I don’t know the number of days, I have put “Yes” if it does germinate at that temperature, “no” if I think it doesn’t and a question mark where I plain don’t know. I would love to know, so if you can resolve the uncertainties, please speak up! I’ve also used the words “best’, “min” and “max” which I hope are self-evident.

Vegetable seed germination

 

Ice cubes over newly sown lettuce seed, to help germination in hot weather. Shadecloth is folded open on the left. Photo Bell Oaks

Soil Thermometers

Soil thermometer.
Photo by Green Living/Taylor

To measure the temperature of the soil outdoors, I recommend a dial-type soil thermometer. Ignore the vague guidelines on Min/Optimal/Max and use the table above. The usual practice is to check the temperature at 9am each day, and if you are unsure, check again the next day. In some cases it is best to get 4 consecutive days of suitable temperatures, or even (in spring!) a few days of rising temperatures.

Harbinger weeds of spring and fall

Flowering Purple (or Red) Dead Nettle, with honeybee.
Credit Kathryn Simmons

The progress of emergence of different weeds in the spring shows us how quickly the soil is warming up. I wrote about that here. In that post you can see photos of flowering chickweed, purple dead nettle, and henbit.

Chickweed seedling.
Photo from UC IPM Weed Gallery

In the fall we will be waiting for the soil to cool enough to sow spinach. I have a blog post about this here, and also photos of those three weeds as seedlings, which is what we are looking for in the fall, as an indication that the soil has cooled down enough for them (and spinach!) to germinate.

Phenology

I have a post about phenology here.You can read some of the details of when to plant by natural signs. For instance, we sow sweet corn when white oak leaves are the size of a squirrel’s ear. I got excited this past weekend (April 10) when I saw wind-driven twigs on the ground with oak leaves definitely bigger than squirrels’ ears. But they were Red Oak, not White Oak.

The chart in that 2013 post has now got corrupted (at least it has on my screen), so here is a pdf

Phenology Record

 

A new bean bed with sunflower landmarks. When lilac is in full bloom, plant beans, squash, corn.
Photo Pam Dawling

Phenology records are a useful guide to when to plant certain crops, and a way to track how fast the season is progressing right where you are. Phenology involves recording when certain wild and cultivated flowers bloom, seedlings emerge, or various insects are first seen. These natural events can substitute for Growing Degree Day calculations. Certain natural phenomena are related to the accumulated warmth of the season (rather than, say, the day-length), and by paying attention to nature’s timetable you will be in accord with actual conditions, which vary from year to year, and are changing over a longer time-scale.

Keeping your own phenology record will help build resilience in the face of climate change. Ours might be interesting to you, but unless you live in central Virginia, you can’t use our dates. You do need to make your own. This can be a great home-schooling project, or a crew I-Spy competition, or a calming end-of-day walk around your gardens.

Root Crops in April – the Hungry Gap

Young Cylindra beets in early May.
Photo Pam Dawling

Root Crops to Plant in Central Virginia in April

We are in cold-hardiness zone 7a, with an average last frost of 4/29. Those in other climate zones can study our Root Crops in May or Root Crops in March for information more useful in their area.

Outdoors we can sow  carrots #4 & #5, parsnips, radishes #2, (last date 4/15, sow on the shoulders of a newly transplanted lettuce bed to save space), beets (last date 4/15, hand sown or with an EarthWay seeder Chard plate, 2 or 3 passes. 1 cup sows 360 ft/110m)

Here we can plant potatoes anytime in April.

It is too late for us to sow any root crops in the hoophouse. (Besides, we want tomatoes!)

Having good stored crops like these beets will feed you through the Hungry Gap.
Photo Pam Dawling

Root Crops to Harvest in Central Virginia in April

As in January, February and March in central Virginia, in most of April there are still no roots to harvest outdoors except overwintered parsnips and maybe carrots, Jerusalem artichokes and horseradish.  Radishes from the first outdoor sowing will be ready at the end of April. We can usually harvest radishes until the end of May. Our hoophouse radishes usually finish in early April. By then it is hot and any remaining radishes bolt.

From storage, if we still have them, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips.

This is the Hungry Gap (see Special Topic for April below)

Colorado Potato beetle late stage larva
Photo Pam Dawling

Other Root Crop Tasks in Central Virginia in April

  • If you are growing your own sweet potato slips, cut 6-12” (15-30cm) slips daily and stand them in water. Once a week, plant rooted slips in 4” (10cm) flats.
  • Hill up potatoes when 6” (15cm) high. Cover half the vine. Repeat after 2 weeks. This deals well with weeds and gives the potatoes more soil to grow into.
  • Potato beetles: Use Spinosad [or Neem] once larvae are seen, if there are more than 50 adults/50 plants or more than 200 larvae/100 plants. If you have fewer, you can leave them alone. Spinosad: Spray when bees are not flying (early morning or late evening.) Shake well, 1-4 Tbsp/gall (1fl.oz=2Tbsp=30ml.) Approx 8-30 ml per liter. Repeat in 6 days. Clean and triple rinse the sprayer. Do not flush Spinosad into creeks or ponds.
  • Thin and weed carrots.
  • Mow cover crop mixes in late vegetable plots when rye or wheat heads up, to help legumes develop.
  • Take rowcover from turnips that were sown 3 or more weeks earlier, to use on newer and more tender crops.
  • Till beds you’ll plant in a week or two, as heavy rain may prevent tilling close to sowing time. My ideal is to till as deep as needed ahead of time, then do a superficial tilling or scuffle hoeing the day before planting. This gives the best weed control.
  • Spread compost on beds you’ll plant in 3 weeks or so, and till in the compost when the soil is not too wet, not too dry.
  • If exposed to 10 consecutive days below 45°F (7°C), celeriac will bolt.
  • Store spring and fall seeds (spinach, peas, beets) in a cool place for the summer.
Vates kale outdoors. An oleracea type, Vates is very cold-hardy.
Photo by Nina Gentle

Special Root Crop Topic for April in Central Virginia: the Hungry Gap

What is the Hungry Gap?

The Hungry Gap happens in temperate climates with four seasons. In winter the short day-length reduces plant growth, and when it’s cold, maybe damp, windy, and overcast, the rate of crop growth drops further. The Hungry Gap is the annual period of the shortfall in local fruit and vegetables. April is the leanest month of the year in northern temperate climates, and the period can extend from January to May. This may be a factor in the origin of the 40 days of Lent.

Spring is not the time of overflowing bounty you might expect – leaves are growing, but not much else. Depending on your particular climate, there may be some vegetables that are winter-hardy. Almost every vegetable lover yearns for more variety than that!

In the spring, any remaining winter vegetables are getting ready to bolt (produce flowers and seeds rather than more leaves). Growers and gardeners are enthusiastically sowing and transplanting new crops, but planting too early would be a sad mistake and it takes time before those new crops can be harvested. That gap between the last of the winter crops and the first of the early spring crops, is called the Hungry Gap.

It’s not a familiar term these days, because importing produce from warmer climates hides the reality. Vegetable consumption in much of the Western hemisphere has shifted from Medieval (leaves and roots) to Mediterranean (“ratatouille vegetables” and salads). Importing or long-distance hauling demands more energy usage, as does the refrigeration they often require in transit.

Also there has been a practice of growing vegetables with artificial heat and light. This is not ecological, as use of fossil fuels contributes to climate change. The food sector accounts for 30% of global energy consumption and produces about 20% of GHG emissions (see the 2011 FAO report). Most of this energy consumption comes from oil and gas in the form of artificial fertilizers and pesticides, on-farm machinery and food processing.

Sweet Potatoes in storage.
Photo Pam Dawling
Sustainable Ways to Bridge the Hungry Gap

How did people survive the hungry gap in times gone by, and what can we learn from those strategies? Eating in the hungry gap used to be both hard and uninspiring – a restricted diet with few options. Adding options involves advance planning and advance work.

  1. Use stored food, such as root crops, winter squash and pumpkins
  2. Preserve fruits and vegetables from other seasons. Consider jams, pickles, canning in jars, freezing, drying, salting and fermenting (think sauerkraut)
  3. Grow more winter-hardy crops that start regrowth early in the spring, and may be harvestable during the winter. Consider covering the rows with rowcover or polyethylene low tunnels.
  4. Grow more perennial crops, such as asparagus, rhubarb, sea kale and sea beet (Beta vulgaris subsp. Maritima, wild beet). Although they take several years to establish, they will then yield earlier in the year than crops grown from seed in spring. Asparagus and rhubarb provide new flavors early in the year and signal the change to come.

    Asparagus in early April.
    Credit Wren Vile
  5. Sow fast-growing cold-hardy crops as early as possible after the winter solstice, for example spring leafy vegetables such as spinach, kale, collards, fast cabbage varieties, and lettuce.
  6. Add crop protection in the form of rowcovers, low polyethylene tunnels (cloches), caterpillar tunnels, high tunnels (hoophouses, polytunnels) to create a warmer environment, trapping heat and humidity and warming up the soil, providing earlier harvests. Protect early sowings of quick crops, like radishes, arugula, land cress, salad greens, and also the first few weeks of newly planted kale, collards, spinach, mizuna, pak choy).
  7. Forage sustainably for edible wild greens as a spring ‘tonic’, even if not a major item in your diet. The strong flavors provide a welcome change after repetitive winter vegetables, and a useful top-up to the supply of produce as stores run low. Spring is one of the best seasons for foraging, but you do have to reliably identify what you’re picking, so get yourself a good guide book or phone app. Ramps, nettles, violets, chickweed, dandelion, garlic mustard, and lamb’s quarters are some of the many wild greens available in spring. See Rustic Farm Life: Wild Spring Greens You Should Be Eating

    Ruby chard.
    Photo Kathryn Simmons
  8. Maximize the number of annual and biennial crops you grow that are in season during the Hungry Gap. Some are mentioned already. Here are more ideas: chard, globe artichokes, herbs, Jerusalem artichokes, kale (one variety is called “Hungry Gap” because it crops during this period. It was introduced to UK agriculture during WWll in 1941), leeks. If your winter climate is mild enough (zone 8 or 9): over-wintered Purple sprouting broccoli, and spring greens (immature close-spaced dark-green cabbages).

    Brassica oleracea ‘Hungry Gap’ – kale
    Photo Chiltern Seeds, UK
  9. Indoor gardening. Grow sprouts and microgreens. These don’t take much advance planning and can perk up a winter or spring meal. Microgreens grow in compost or on special “blankets”, but sprouts are generally grown in jars or trays. Pea shoots are an easy one to start with, and you can use dried peas from the supermarket. When sprouting it is important that you buy organic seeds, to be sure that they have not been treated with any chemicals. Rinse your sprouts twice a day, and keep everything clean.

Read more about the Hungry Gap

https://www.youtube.com/watch?v=FbZfTAYDA88

https://theunconventionalgardener.com/blog/what-is-the-hungry-gap/

https://sustainablefoodtrust.org/articles/spring-plate-eating-hungry-gap/

https://www.farmdrop.com/blog/hungry-gap-seasonal-british-produce/

This is the last post in the monthly series on root crops. You can see them all here:

Root Crops in May

Root Crops in June

Root Crops in July

Root Crops in August

Root Crops in September

Root Crops in October

Root Crops in November

Root Crops in December

Root Crops in January

Root Crops in February

Root Crops in March

Workhorse Crops for the Month

Next month I will start a new monthly series. Workhorses are crops that are reliable under a wide range of conditions, including weather, soil, date and other variables. Some are easy to grow, some pump out lots of food, some are “insurance crops” like chard that stand in your garden until you need to harvest them. Part of my motivation for this series is to help all the “Covid-steaders” who started growing food during the pandemic and want to up their game without investing a lot more time. Part is to help established gardeners and growers who need to make a living while dealing with the changes the past year has brought to their markets and to our climate. We need some easier days!

 

Root Crops in March

We shovel many wheelbarrows full of compost to our raised beds every year.
Photo Wren Vile

Root Crops to Plant in Central Virginia in March

As soon as the soil is dry enough and not frozen, we spread compost on the raised beds we plan to plant in February and March, and till in the compost. We make ourselves a Spring Start-up Plan, so we know where to focus our energy when the weather gives us a chance.

Spring Start-up Plan

We aim to spread compost 4-6 weeks before planting, rototill 2-4 weeks before planting, and prep the bed a week or two before. This is more time than we allow later in the year, but in early spring it’s good to seize the opportunities that arise and not take the weather for granted.

This means in January we compost and till beds for spinach, turnips and our first carrots. In the first half of February we till the turnip beds and any beds of winter-killed oats cover crops that we will be planting soon. We compost the first lettuce bed, the kale and collard beds, and those for cabbage, beets, more carrots, senposai and peas (all have planting dates March 9 to 15). In the second half of February, we compost the third carrot bed and till the ones we already composted. In early March we till the third carrot bed.

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

Once we get to March, day length has increased and temperatures are starting to climb. There is a noticeable increase in the rate of germination and growth (unlike for our February sowings, which are rooted in faith and optimism!) All being well with the weather (it’s extremely wet this year!), in early March, we direct sow turnips (3/6- 3/16), and radishes #1 (Cherry Belle or some other fast variety)

In mid-March, we can transplant kohlrabi. And we direct sow carrots #3 and beets. See below for more about beets. In late March, we direct sow our carrots #4, and more radishes and beets. We can sow kohlrabi if we have no transplants, and thin to 6” (15 cm) later.

Potatoes

A row of potato seed pieces ready to cover.
Photo by Wren Vile

We plant potatoes when the daffodils bloom, usually mid-March. Last year I wrote an extensive series of posts about growing potatoes.

See Planning to Grow Potatoes Again, the last part of a monthly series on growing potatoes, a dietary staple.

PART ONE: Planting potatoes (April)

PART TWO: Growing potatoes (May)

PART THREE: Potato pests and diseases (June)

PART FOUR: Harvesting potatoes (July)

PART FIVE: Storing potatoes (August)

PART SIX: Planning to grow potatoes again (September)

Beets

Detroit Dark Red beets in early June sunshine.
Photo Pam Dawling

Beets are workhorse root crops that thrive in mild weather, store well, and are popular traditional foods. They are crops that can provide high yields for the time invested.

Beets come in several types, round, top-shaped and long. The size and quality of the greens is a factor if you sell bunched beets with tops, or use the tops for greens. We like the 6” (15cm) long Cylindra/Formanova/Forono ones (55 days to maturity, OP). They are very tender and easy to cut into regular slices, for pickles or cooking. The skins come off easily, and the flavor is very sweet and the texture tender.

Among round ones we like Ace (50 days to maturity, F1 hybrid), and Detroit Dark Red (60d), a tender open-pollinated variety. Detroit Crimson Globe is said to maintain better flavor in hot weather than most others, which can develop off-flavors. Early Wonder Tall Top (48d), is also open-pollinated. Lutz Green Leaf (70d) is a big long-storage variety. There are also golden beets, white beets and candy-striped Chioggia beets, although in my experience, what they gain in appearance they lose in flavor and tenderness.

Beets seeds average 35,000 /lb. 2,200/oz, 80 seeds/gm. 1,285 seeds (2/3 oz, 18gm) sow 100’ (30m).  150’/oz, 2,300’/lb., 9 lbs/acre. 315,000 seeds/acre. Yield can be 40 lbs. (18kg) greens, 100 lbs. (45kg) roots/100’ (30m), or 14,000 lbs/acre, 2540 kg/ha.

Beets need a pH of 6.0-7.0, preferring 6.5-6.8.  They require abundant potassium, which can be supplied by woodash. Boron deficiency can show up in beets as internal browning, or dark dead tissue, as well as distorted leaf growth. It is most likely to occur in alkaline soils after long hot, dry spells. Beets can suffer from “zoning,” (white rings in the roots), if there are acute weather fluctuations.

Young Cylindra beets in early May.
Photo Pam Dawling

Sow beets whenever the soil is between 50°F (10°C) and 95°F (35°C), so long as you can keep the surface damp. With beets we do a single sowing in mid-March and more in early August. We are growing for fresh use, pickling and storage, but not bunch sales, so we don’t need to do frequent sowings. For a continuous supply of greens and baby beets, sow every 2 weeks from spring until 8 weeks before regular frosts usually occur, or about 10 weeks before a heavy freeze is expected.

We direct sow either dry beet seed, or some we have presoaked for 1-2 hours. Beet seed drowns easily: don’t use too much water or soak for too long.  Sow 0.5″(1.2cm) deep in spring, deeper in hot summers, but never more than an inch (2.5cm) deep. We sow an inch (2.5 cm) apart in single rows 8-10” (20-25cm) apart. Others sow in bands 2-4″ (5-10cm) wide, at about 15 seeds/ft (2cm apart), with bands 12-18″ (30-45cm) apart. As for carrots, avoid soil crusting.

It is important to get good soil contact for the corky seedballs, so tamp or roll the rows after seeding. Keep the rows damp, by watering as needed for the 5-17 days they take to emerge. Beet seeds are actually seed balls (clusters of seeds) so each one you plant will produce several seedlings right next to each other. “Singling” the beets is an important step, and they will benefit from hoeing, thinning and weeding. Beets deal with weed pressure and crowding a lot better than carrots do, so if you have to choose which to weed, the carrots win! We thin in stages, so that at the second thinning, the baby beets can be used as a crop.

Detroit Dark Red beets , harvested, washed and trimmed.
Photo Pam Dawling

For mature beets, allow each a minimum of 3” (7.5cm). The Cylindra beets can be left a bit closer, and will push themselves up out of the soil as they grow. Know and Grow Vegetables recommends establishing 5 plants per square foot (54 per square metre) for early beets. This translates to a final spacing of 4 x 7” (10 x 18cm). For maincrop beets, aim for 10-15 per square foot (107-161 per square metre.) For maximum total yields of small sized roots use a spacing of 1 x 12” (2.5 x 30cm).

This info about growing beets is excerpted from my book Sustainable Market Farming. See the book for more on pests and diseases, harvesting and storing, and seed saving.

In our climate, beets are one of the crops that can be sown in spring and again in early fall (actually August for beets here in central Virginia). See my August post Sowing beets, radishes and kale, transplanting cabbage.

See Root Crops in August for more about fall beets. Beets can be tricky to germinate in hot weather, but to get good storable-sized roots, we need to get them established by 8/20. (Two months before our average first frost.)

Root Crops to Harvest in Central Virginia in March

From storage, if we still have them, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips.

As in January and February in central Virginia, there are no roots to harvest outdoors in March except parsnips, Jerusalem artichokes and horseradish. We do have horseradish, but not the others, but we don’t have a lot of demand for that.

We have had outdoor night temperatures of 12°F/-11°C and 11°F/-13°C. This winter we had some carrots outdoors over the winter. We harvested them and got 150 pounds from 400 row feet. Not a high yield but they do taste good! They are Danvers 126. The intended sowing date was August 14, but we didn’t get the seed in the ground until September 5.

A crate of overwintered Danvers 126 carrots

In the hoophouse our #4 radishes will get harvested during March. Our #5 radishes, sown 12/23, will then feed us until around April 7.

We still have some of our good size second hoophouse turnips until mid-March. We sowed those on October 25. The greens are a bit ragged now and less appetizing for cooking, although on cold rainy days, they make for more pleasant harvesting than any greens outdoors! Turnip greens (and Russian kale) are our last hoophouse greens to bolt, so we value them.  We need to harvest the turnips to make space to transplant our hoophouse tomatoes in mid-March.

Other Root Crop Tasks in Central Virginia in March

  • Green chit (pre-sprout) seed potatoes, see Planting potatoes .
  • Buy seed potatoes for June planting, and refrigerate them. Keep at 40-50°F (4.5-10°C) in the dark, until 6/1.
  •  Test and condition sweet potatoes for 2 to 4 weeks at 75-85°F (24-29°C), 95% humidity if you are planning to grow your own sweet potato slips.
Sweet potato sprouting slips.
Photo Pam Dawling

Special Root Crop Topic for March in Central Virginia: What makes vegetable crops bolt?

Green mizuna bolting in our hoophouse in mid April. Although the mizuna is bolting, the Scarlet Frills is hanging in there.
Photo Pam Dawling
  • Bolting is the term for plants going to seed. Rather than grow more leaves and bigger roots, the plants develop stems, skinnier and fewer leaves, then flower buds, flowers and seeds.
  •  The plants are switching their energy to survival of the species in the face of unsuitable conditions.
  •   When a plant starts to bolt, it is usually a sign to expect a poor harvest. It is also an indication that the plant will decline in terms of flavor. Lettuce become bitter. As long as you can harvest leaves or roots that are not too woody, you can eat bolting plants. But they do become too tough and inedible at some point.
  •  Crops inclined to bolt include arugula, basil, beets, brassicas (such as cabbage), carrots, celery, leeks, lettuce, onions, turnips and spinach.
  •  Bolting is initiated by plant hormones called gibberellins.
  •  Although bolting is usually seen on crops approaching maturity, it is initiated much earlier.
  •  It’s a complex business, understanding the various triggers to bolting.
  •  Stress factors, including changes in day length (usually an increase), high temperatures or low temperatures at particular stages in a plant’s growth cycle, plant size, plant type, root stress, and stresses such as insufficient water or minerals.
  • Increased day length: Bolting can happen when day length increases as summer approaches. This can be a problem if you planted your seeds too late in the spring. The extra hours of light trigger annual plants to run to seed.
  •  High soil temperatures: As soil temperatures increase in summer, plants are triggered to begin seed and flower production. This isn’t a problem late in the crop’s life, after bountiful harvests. But, when spring has unusually hot weather or if you plant crops too late into the growing season, your crop may bolt before any harvests. Cool weather crops like lettuce and spinach will bolt in spells of hot dry weather.
  • Cold temperatures: A sudden cold snap in spring can signal to biennials (such as onions, leeks, beets and carrots) that “winter” has happened and it’s time to develop seeds for the next season. If you start these crops too early in the calendar year, you risk exposing young plants to cold weather, priming the plants to develop flower stems as soon as the weather warms up again. 
  •  Plant size:
  •  Annual plants grow from seed, flower and set seed all in one year. That can be spring to winter or fall to summer. Annual crops are sensitive to daylength, and will start making flowers as the daylength (and temperature) increase. When an annual plant bolts, it’s the beginning of the end.
  • Biennial plants (onions, leeks, carrots, beets, and chard) grow big the first year, then seed the second year. They can initiate flowers in the first yea, due to unsettled weather early in the season. Bolting usually occurs after a prolonged cold spell, often during an immature stage. Cold nights, hot days and late frosts may also contribute to premature flowering.
  • Root stress: Bolting caused by root stress typically happens when you disturb a plant’s root system by transplanting, or if your plant runs out of growing space in a container that’s too small.
  • Stresses such as insufficient minerals or water: Healthy soil with plenty of nutrients and balanced moisture levels will encourage quick growth. Every grower should aim for this balance, especially those in hotter climates where it’s a race to plant leafy salads, cooking greens and root crops before the hot weather fights against you.

Collards bolting in late March.
Photo Pam Dawling

Next week I will provide information on avoiding, preventing and postponing bolting.