August 2021 Sustainable Farming News Roundup

Fredericksburg Food Co-op, https://fredericksburgfood.coop/  320 Jefferson Davis Hwy, Fredericksburg VA 22401. Phone: (540) 940-6615 Tuesday August 24, Time: 6-7 pm

Fredericksburg Food Coop

Fall Vegetable Production

60 min Discussion and Q and A This is a conversation, not a powerpoint, and will be held outdoors on the dining patio. There will be handouts with lots of resources for more information.

My books will be available for sale and signing. Bring your old dog-eared copies, I’m very happy to sign those too!


Seven Springs Fair

Mother Earth News Fair at Seven Springs, Pennsylvania 

(September 17-19, 2021)  The in-person fair is going to be cancelled.

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See the Events page for workshops in October, November, January and onwards.

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Harvest to Table has a list of August Vegetable Garden tasks, if you need that. I can always find some useful tips on this site.

Harvest to Table logo

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For gardeners in central Virginia, the Piedmont Master Gardeners monthly Garden Shed newsletter offers August in the Edible Garden by Ralph Morini, and The Nutritional Value of Leafy Green Vegetables by Penny Fenner-Crisp (including a good resource list), and several other topics. Each newsletter has a photo of a different garden shed. Here’s this month’s (with hammock!)

Piedmont Master Gardeners Shed newsletter. (Some sheds have a hammock!)

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Future Harvest Beginning Farmer Training Program

For the next scale up, beginning farmers in the Chesapeake region can apply to Future Harvest’s Beginner Farmer Training Program (BFTP)  I have the honor of being one of their Level 3 consultants.

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Organic Growers School logo

Organic Growers School, based in Asheville, North Carolina, is also open for applicants for their Journeyperson program and their year-long Farm Beginnings program

Journeyperson Program is for those who have been farming for 3 years and are looking to grow a farm business. Join Nicole DelCogliano, August 26th, at 7 pm for a Journeyperson Info Session. via Instagram Live! Nicole will answer your questions about our Year-Long Journeyperson program, (which starts in November 2021 and ends in October 2022), and discuss options to meet your farming needs. 

 

Organic Growers School Farm Beginnings Program

Farm Beginnings is a year-long training program, including Whole Farm & enterprise
planning,  Connection to a farmer network, Growing season learning plan, On-Farm Field days & workshops. This is for those who have already considered making a career of farming, and have taken some steps in that direction. Deadline for this year is September 18. Click the title link and watch the video.

There are also field days, skill sessions, work exchanges, internships and the Farm Dreams program for those at an earlier stage of the process. To help you choose, click Growing the Next Generation of Farmers, and check out this worksheet.

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SARE logo

Following on from my recent post about planning winter cover crops, here’s something else useful: SARE has a new video “Cover Crops and Soil Health” which illustrates how producers can use cover crops to improve productivity and sustainability. In just a few short minutes, “Cover Crops and Soil Health” outlines how cover crops can build soil structure, protect water quality, suppress pests and improve a farm’s bottom line.

Combining cover crops and reduced tillage can also help farmers:

  • Manage soil nutrients
  • Reduce erosion and compaction
  • Improve water holding capacity and infiltration
  • Reduce input costs
  • Increase yields

“Cover Crops and Soil Health” is now available for viewing and sharing at www.sare.org and on YouTube. Farmers, ranchers, educators and other agricultural professionals may download or embed the video without modification into websites or other noncommercial educational presentations. The entire “What is Sustainable Agriculture” series is also available on YouTube. This video series was produced through a collaboration of the Sustainable Agriculture Research and Education (SARE) program and Pixeldust Studios.

Crimson clover cover crop starting to flower.
Photo Kathryn Simmons

Planning Winter Cover Crops

 

A cover crop mix of winter rye, hairy vetch, Austrian winter peas and crimson clover.
Photo Bridget Aleshire

If you haven’t already made a plan for winter cover crops, this is a good time to do it. Having plants growing through the winter, or at least into the winter until they get killed by cold temperatures, will improve your soil both physically (the roots hold the soil in place, preventing erosion, and they open up channels that improve the drainage) and biologically (the soil microorganisms thrive when they have active plants to cooperate with, exchanging nutrients). Cover crops will also reduce the number of weeds you have next year, because they crowd out weed seedlings. In some cases they even inhibit weed seeds from germinating.

I have some slideshows about cover crops, and am including one at the end of this post.

Choosing the “perfect” cover crops can be confusing, but any is better than none, so I encourage you to experiment and keep records, so you can improve your choices each year. It helps to know your first frost date, and your winter-hardiness zone (the lowest temperature your garden is likely to encounter). A two-week delay in sowing can seriously reduce the effectiveness of the cover crop, so follow these guidelines if you can.

A cover crop of overwintered oats the year they didn’t die.
Photo Pam Dawling

Short Simple Guide to Winter Cover Crops

  1. If the area has been fully harvested of food crops by 60-80 days before frost, sow a frost-killed cover crop or even a fast-growing food crop. Buckwheat, soy, cowpeas, spring peas, sunnhemp, Japanese millet, sorghum-sudangrass will frost-kill. Forage radish lab-lab bean or bell beans will die back and leave almost bare soil. Don’t sow a winter cover crop yet. If sown too early, oats head up in the fall and even drop seed.
  2. If the area is clear of vegetable crops by 40-60 days before frost, sow oats to winter-kill. If possible add a legume (soy and spring peas are easy, and will be killed by the frost, so they won’t complicate food crops next year). For us with a first frost date of October 14, the cut-off date for oats is September 7. This would be after growing early sweet corn, spring broccoli, cabbage, spring-planted potatoes or early season spinach, lettuce, beets, carrots. Oats will winterkill completely at 6°F (-17°C) or even milder than that, leaving the plot quick to prepare for early crops next year. So plan to put your early crops where you had oats in the winter. See the slideshow for more about oats.

    Crimson clover cover crop in flower.
    Photo McCune Porter
  3. If the area is ready for cover crops 20-40 days before frost, sow winter wheat. Add a legume such as crimson clover, if you won’t need to prepare the area before it flowers (in central Virginia 4/16-5/2, most usually around 4/20). You get the most nitrogen from the legumes if they reach the flowering stage before you kill them off in spring. If you have a legume that doesn’t reach flowering, it’s not the end of the world, you just get less nitrogen for your money. It is too late to usefully sow cover crops that are not frost-hardy, or even oats, which won’t make enough growth before getting killed.

    Cover crop of winter rye, hairy vetch and crimson clover.
    Photo Kathryn Simmons
  4. If the area is ready for cover crops up to 10 days past the frost date, sow winter wheat or winter rye and hairy vetch or Austrian winter peas. Winter rye is hardier than any other cover crop and can take later planting dates. But it is a bit harder than wheat to incorporate in the spring. Austrian winter peas can be sown later than other legumes.
  5. If you are up to 3-4 weeks past your average frost date, (we choose November 7 here, where our average first frost is October 14), sow winter rye alone. It’s too late for any legumes.

    Cover crop of winter rye still small in March, but holding the soil together.
    Photo Pam Dawling
  6. If you are later than 3-4 weeks past your average first frost date, leave the weeds or crop remains growing. It’s too late to sow a cover crop, and you’ll do more harm than good tilling up the soil. You can mow the weeds anytime you see lots of flowers and seed heads. The weed roots will hold the soil together and help feed the soil microorganisms until early spring. Be prepared to act soon in spring, so you don’t get weed seeds.
Quick Guide to Winter Cover Crops.
Pam Dawling

More Options for Each of These Time-frames

  1. 60-80 days before frost: You could follow a frost-tender cover crop with an over-wintering cover crop, for best effect. If you leave the dead tender cover crops in place, in early spring the winter weeds will start growing in the open space, so be ready for fast action. For the very earliest spring crops, forage radish lab-lab bean or bell beans will die back and leave almost bare soil. While still growing, they suppress weeds. BUT fast-maturing spring vegetables will not do well with no-till cover crops unless you add N fertilizer, as they need nitrogen more quickly than can be got from no-till.
  2. 40-60 days before frost: Austrian winter peas, crimson clover, or red clover are other options for legumes, but they won’t die when the oats do. They are relatively easy to incorporate in spring. Frost-killed cover crops can also be combined with oats. Or for a cover crop to survive the winter, sow winter barley or winter wheat with Austrian winter peas, crimson clover, hairy vetch, red clover, fava beans. Hairy vetch takes a few weeks longer than crimson clover to reach flowering. Which you choose will depend what you want to grow there next spring and when you need to plant it. After oats or other winter-killed cover crop, we like to plant our early spring food crops, peas, cabbage, broccoli, carrots, March-planted potatoes, spinach and the first sweet corn.

    Cover crop height and thickness in late April.
    Photo Kathryn Simmons
  3. 20-40 days before frost: Winter rye, or winter barley are also options for the cereal grain part of the mix, if you have those seeds on hand. In central Virginia, it’s a mistake to sow rye as early as August, as it can set seed. Austrian winter peas, or red clover are other legume options if that’s what you have. Sometimes it pays to use what you already have, as it may not give good germination if saved over to next fall. Winter rye needs 3-4 weeks after tilling in, in spring, to break down and to disarm the allelopathic compounds that stop small seeds germinating. Plan for the next food crops to be ones planted after late April, such as late corn plantings, winter squash, transplanted watermelon, tomatoes, peppers, sweet potatoes, June-planted potatoes, fall brassicas, and second plantings of summer squash, cucumbers, beans.
  4. Up to 10 days past the frost date: it’s too late for clovers. Austrian winter peas winter-kill in zone 6, but are hardy in zone 7. Hardy to 0°F (-18°C). AWP bloom in late April at Twin Oaks, before hairy vetch. Suitable crops in the year before using Austrian winter peas are the late-finishing winter squash, melons, sweet potatoes, tomatoes, peppers, middle sweet corn, June-planted potatoes. The same group of crops are suitable for following AWP, as they are planted after May 1. You can sow AWP several weeks later than clovers, but at least 35 days before first hard freeze (25°F/-4°C) – in zone 7, 8/10–10/24 (11/8 is sometimes OK)

    Winter rye headed up. Mow or turn it under very soon! Don’t let it shed seed.
    Photo Pam Dawling
  5. Up to 3-4 weeks past your average frost date: no really, it’s too late for any other cover crop. If you don’t have winter rye, don’t till! Leave the weeds, see below.
  6. Later than 3-4 weeks past your average first frost date: no, really, do not till! You could mow and tarp, to kill the weeds before spring. I’m not sure what the soil life thinks about that, though! You could mow again in early spring, or till and sow oats, if you won’t be planting a food crop in the following 8 weeks, giving the oats time to make respectable growth before turning them under.

Create a crop rotation for vegetables that includes good cover crops

If you include winter cover crops when planning a crop rotation for your vegetables, you can tweak your plan to maximize your cover crop opportunities. Here’s the steps:

 Figure out how much area is needed for each major crop (the ones needing the largest amount of space).

  1. Measure and map the space available
  2. Divide into equal plots big enough for your major crops
  3. Group compatible crops together to fill out each plot
  4. Set a good sequence, maximizing cover crop opportunities
  5. Include best possible cover crops at every opportunity
  6. Try it for one year, then make improvements

For more details, see my slideshow Crop Rotations for Vegetables and Cover Crops on SlideShare.net

Advanced Options for Winter Cover Crops

Sweet corn with undersown soybean cover crop. Photo Kathryn Simmons

Undersowing

Sometimes you can undersow the cover crop between the rows of a growing food crop, to take over after the food crop dies of frost or mowing. We do this with our last planting of sweet corn, and with fall broccoli and cabbage.

Timing is critical: Sow the cover crop late enough to minimize competition with the food crop, but early enough so it gets enough light to grow enough to endure foot traffic when the food crop is harvested. The leaf canopy of the food crop should not yet be closed. Often the best time is at the last cultivation, often about a month after planting the food crop. With vining food crops, it’s important to sow the cover crop before the vines run.

Choose vigorous food crops, but cover crops that are only moderately vigorous. Ensure the seedbed is clean and the soil crumbs small enough. Use a high seeding rate, whether broadcasting or drilling, and irrigate sufficiently.

A no-till cover crop mix of winter rye, hairy vetch, Austrian winter peas and clover.
Photo Bridget Aleshire

No-till Winter Cover Crops

In the spring, kill the cover crop without tilling it in, and plant food crops into the dying residue. There are three ways to kill cover crops without herbicides:

  1. Winter-killed cover crops for early spring food crops
  2. Mow-killed cover crops.
  3. Roll-killing (but it usually requires special equipment).

We have had one year in 10 as a no-till year. We use no-till cover crops before Roma paste tomatoes, which are transplanted in early May. We don’t need early-ripening for these, making them a good no-till food crop. The soil under no-till cover crops stays colder than tilled soil, slowing the plant growth down.

Late-spring transplanted crops such as late tomatoes, peppers, eggplant, Halloween pumpkins, or successions of cucumbers and squash can do very well after a winter-hardy legume-grass mix no-till cover crop.

To be an effective mulch, you need to get a thick sturdy stand of cover crops, which means sowing in plenty of time, and being generous with the seed. To make the timing work, you need a previous food crop that finishes before the sowing date 4-5 weeks before the average frost (that’s September 7-14 for us).

Timing is also critical in the spring. For maximum N, the legumes in the mix will be flowering right when you need to plant the food crop. Mow the cover crop mix close to the ground, and plant right into the stubble. Transplants or big seeded crops work well. The ground will be relatively hard – you probably can’t make a furrow for small seeds).

It’s not all over with the weed-prevention after that. In our humid climate the no-till mulch biodegrades after 6-10 weeks. In July we roll hay between the rows, to top up the mulch.

Cover Crops for Vegetable Growers 2019 60 mins

Haraka No-Till Rolling Punch Planter

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

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

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

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

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

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

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

Haraka Planter seed plate and appropriate seeds
Photo Eden Equipment

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

Pushing the Haraka planter.
Photo Pam Dawling

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

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

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

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

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

Specifications:

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

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

Specifications:

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

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

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

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

Book Review: The Living Soil Handbook by Jesse Frost

Cover of The Living Soil Handbook by Jesse Frost

The Living Soil Handbook

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

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

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

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

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

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

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

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

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

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

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

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

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

Composts come in four types (recipes included):compost

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

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

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

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

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

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

Jesse Frost

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Root Crops in February

 

Large Smooth Prague celeriac. (Currently sold out Feb 2021)
Photo Southern Exposure Seed Exchange

Root Crops to Plant in Central Virginia in February

We sow no root crops in our hoophouse in February. It’s too late for radishes or turnips. If you are in a place colder or darker than winter-hardiness subzone Zone 7a, with an average minimum temperature of 0° to 5° F (-18°C to -15°C), see Root Crops in January.

If the soil outdoors 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. Root crops that we sow outdoors here in February include carrots #1 and turnips in mid-February, and carrots #2 and radishes in late February. It’s true not much growing happens in February, but it helps us if we are able to get some crops planted early, leaving us more capacity for other crops once those are in the ground. And if the soil isn’t dry enough, we just do those jobs as soon as we can. We would hate to miss an opportunity!

Carrot Bed Prep

One of our many carrot beds, looking good.
Photo Kathryn Simmons

Carrots do very poorly with competition from weeds or too many other carrots. You can make use of the Stale Seedbed Technique, preparing the bed ahead of time, and flaming or hoeing one or more flushes of weeds as they germinate. I’ll do a separate blogpost on flame-weeding soon, as I have too much info to squeeze in here. It works so well, it feels like cheating!

Carrots are small seeds, needing a fine tilth (small soil particle size and good texture – not likely to crust or blow away).  Good information on crop spacing for maximum yields, or biggest vegetables is in an out of print book, The Complete Know and Grow Vegetables by JKA Bleasdale, PJ Salter, and others. For maximum total yield of carrots, they recommend 1.5” x 6” (4 x 15cm). You get medium sized carrots. For early carrots go with 4 x 6” (10 x 15cm) to minimize competition and get rapid growth. If you want to have rows more than 6” (15cm) apart, calculate the area of these optimum spacings, then divide by your chosen row space. For example, if your rows are 12” (30cm) apart, the carrots can be as close as 0.75’ (2cm) if total yield is more important than individual size, or 2” (5cm) for fast early carrots. We do five rows in a 4 ft (1.2m) bed, so the rows are about 10” apart, with the outer rows 4” (10cm) from the bed edge.

Young Carrot Plants After Thinning. Photo Kathryn Simmons

Carrot Thinning and Weeding

Remember to thin carrots as soon as you can see them well enough to do so. We usually hoe between the rows first, then crawl along thinning and weeding. It does take time! But you won’t get good carrots without thinning, unless you either have a precision-seeder that drops one seed per inch, or pelleted seed which you can sow at one per inch. Precision seeders like the Jang are expensive, but worthwhile if you need to use it every week. Pelleted seed costs more than raw seed, and its big advantage is traded off for two other disadvantages: The soil has to be kept well-watered until germination or else the clay coating will imprison the seed forever, and the seed does not store for long – don’t keep any over for next year.

Greenhouse Root Crop Sowings for Transplants

The only root crops we ever transplant are celeriac and kohlrabi (a stem vegetable really, not a root). I have transplanted many things and I am skeptical of books saying this or that can’t be transplanted, but not beets or rutabagas, which I hear people transplant as soil blocks or plugs. So try it if you think it will help.

Celeriac

Flats of celeriac seedlings.
Photo Kathryn Simmons

We have grown both Diamante (100 days from transplanting) and Large Smooth Prague (110d), and strongly prefer Diamante, as it seems to us to be more tolerant of warm weather, less prone to rot, and easier to clean. Several growers say that Diamante and Brilliant are virtually indistinguishable.

This crop likes rich soil with lots of organic matter, some shade from mid-day and afternoon sun, and ample water without sitting in waterlogged soil. We make sure to choose beds in a shadier part of the garden. Celeriac can rot if too damp, so keep it weeded and remove some of the lower leaves to improve airflow. A pH 5.8-6.7 is ideal. Celeriac can benefit from seaweed as a foliar spray, or side-dressing with compost during the long growing season.

Celeriac requires long steady growth, and the challenge is to prevent checks to growth. The Virginia climate is on the warm side for celeriac, it prefers cooler areas, but we have good success if we pay attention at a few critical times. Celeriac can tolerate frost quite well, so there is no hurry to harvest in the fall.

Sow seeds 1/8″(3mm) deep, and keep the soil surface moist. The minimum germination temperature is 40°F/5°C, and the optimal range 59–70°F/15-21°C. Germination is slow, typically 14 to 21 days, and it takes 10-12 weeks to grow to transplant size, so start in plenty of time. We sow in open flats, then spot out (prick out) into deeper flats. We sow February 10, which is about 10 weeks before our last frost date. Celeriac can be sown from 67 days before the last frost date to 184 days before the first fall frost date, but you don’t get large roots unless you have plenty of growing time.. If your climate includes long chilly springs, I’d suggest starting 12 weeks before the last frost date.

Emergence takes at least 12 days at 59°F/15°C and 7 days at 68°F/20°C. The ideal temperature is 68°F/20°C day, and 59°F/15°C at night. The fluctuating temperatures, with nights cooler than days by 9°F/5°C, help speed germination. Another factor when choosing germination temperature to aim for, is that at 59°F/15°C, only 40% of the seeds produce seedlings, compared to 97% at 68°F/20°C.

Celeriac should not be hardened off by reducing temperatures, as that can cause them to bolt. More than about 9 night temperatures below 55°F/12°C will cause bolting. Plants can have their watering reduced to help them get ready for the big outdoors. Use rowcovers if a cold spell arrives after you have planted them out, or if you know cold weather is likely to return. Falling apple blossom is a phenology sign that conditions are suitable.

See Root Crops in May for transplant info

See SESE’s Celery & Celeriac Growing Guide for growing information.

Kohlrabi

Harvested kohlrabi, Early White Vienna and Early Purple Vienna.
Photo McCune Porter

Kohlrabi is very easy to grow, treat it just like cabbage or kale.

It can be direct-seeded, but for an early crop, especially if you live in a climate like ours where spring turns into summer very quickly, use transplants. We don’t grow a lot, only 180 feet (55m) in total for 100 people. We also grow kohlrabi in the fall, transplanting bare root transplants from nursery seedbeds around August 3. We grow twice as much in fall as spring, because we can store them for winter.

We have grown both Early White Vienna and Early Purple Vienna. Growing both provides for pretty harvests. We sow February 8 at 4 seeds/inch (0.5 cm apart) in open seed flats, aiming to have the plants spotted out, hardened off and transplanted outdoors with rowcover on March 13. Fast work!

Root Crops to Harvest in Central Virginia in February

Hakurei turnips harvested late January.
Photo Pam Dawling

As for January, in central Virginia, there are normally no roots that we could be harvesting outdoors in February except parsnips, Jerusalem artichokes and horseradish.  We do have horseradish, but not the others. Of course, you can only dig up root crops if the ground is not frozen!

We have had outdoor night temperatures of 16°F/-9°C and 12°F/-11°C. This winter we have some carrots “growing” in the fresh air and some late-sown beets under rowcover. I don’t think we’ll get roots from the beets, but the leaves might make a nice change from brassicas as cooking greens.

In the hoophouse our radishes #3 (sown October 30) will come to an end by 2/1. Our #4 radishes will get harvested this month. Our #5 radishes, sown 12/23, will feed us from then until around April 7

We still have some of our first turnips (sown around October 13) until mid-February, and they have reached a really good size, thanks to early thinning. This month we can harvest the second sowing (October 25). We thinned turnips #2 in early January. They are looking good too.

Red Round turnips in our hoophouse in late January.
Photo Pam Dawling

We have not yet needed to unroll our inner rowcovers in the hoophouse. We wait until we expect it to get down to 8°F (-13°C) outdoors, as we like to avoid extra work!

Other Root Crop Tasks in Central Virginia in February

Potatoes stored in crates in our root cellar.
Photo Nina Gentle

Check stored vegetables

Stored crops need to be checked for decay at least once a month, preferably once a week now the days are getting longer and the temperatures will get warmer. From storage, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips, if we grew them.

Special Root Crop Topic for February in Central Virginia

Wrap up the winter planning

Our garden planning wraps up by mid-February, with all the budgets, crew selection and shift decisions (afternoons in cold weather, mornings in hot weather –  we’re mostly half-day gardeners, with one or two stalwart all-day workers)

Order summer cover crop seeds

Buckwheat cover crop in flower.
Photo Pam Dawling

For early spring, if we find an area without a winter cover crop and we realize we won’t plant it with a vegetable crop for at least 8 weeks, we sow oats. They will smother weeds and add organic matter to the soil when you till them in.

If you have not already ordered summer cover crop seeds, this would be a good time to do so. Cover crops suppress weeds, add organic matter, feed the organisms in the soil and attract beneficial insects, birds and amphibians to feed and reproduce. Biodiversity encourages ecological balance that can help reduce plant diseases and pest attacks. Have a goal of No Bare Soil. Seek out odd spaces to fill with cover crops.

Once frosts are past, buckwheat is an easy cover crop. Its flowers attract beneficial insects, and it is a very manageable (not too tall) fast-growing crop. Buckwheat can be in and under in a month.

Just as fast is mustard, but we don’t grow that because it’s a brassica and we grow a lot of brassica food crops. Keeping a good crop rotation is important to us. Also we have harlequin bugs and we don’t want to feed them year round.

Sorghum-sudangrass hybrid is a fantastic, huge warm weather grass type cover crop, but don’t grow it if you have only a lawnmower, a scythe or a nylon line weed whip to cut it down! For smaller scale gardens, choose Japanese millet.

Soybeans, southern peas and sunn hemp are easy legume cover crops for warm weather, providing nitrogen for the next crop.

Cover cropping is a big topic. See my book Sustainable Market Farming for more. Here I’m just pointing you in the right direction enough to order seeds soon. You can read up more later.

Vegetable harvests, articles on seed saving and garlic planting, workshop on cover crops.

 

Close up of Cow Horn okra pods.
Photo Kathryn Simmons

There are several aspects of vegetable harvesting. In this post I will look first at maturity indicators, then at four ranges of cold-hardy crops for harvest at various stages of winter, followed by a reminder of the order for harvesting storable crops, according to the coldest temperature they can take. After that I have links to a couple of other websites with great information on these topics, a mention of two articles on seed saving  and one on garlic planting I have in Growing for Market magazine. And a link to a Mother Earth News Fair Online workshop on establishing winter cover crops.

Harvest and Maturity Indicators

Don’t harvest too soon or too late. How do you know when it’s ready to harvest? Different factors are important for different crops. Use all your senses.

  • Size: Cow Horn okra at 5”/13 cm (others shorter), green beans a bit thinner than a pencil, carrots at whatever size you like, 7”/18 cm asparagus, 6”/15 cm zucchini
  • Color: Garden Peach tomatoes with a pink flush. The “ground spot” of a watermelon turns from greenish white to buttery yellow at maturity, and the curly tendrils where the stem meets the melon to turn brown and dry. For market you may harvest “fruit” crops a bit under-ripe
  • Shape: cucumbers that are rounded out, not triangular in cross-section, but not blimps. Sugar Ann snap peas get completely round before they reach peak sweetness.
  • Softness or texture: eggplants that “bounce back” when lightly squeezed, snap beans that are crisp with pliable tips. Harvest most muskmelons when the stem separates easily from the fruit (“Full slip”).
  • Skin toughness: storage potatoes when the skins don’t rub off, usually two weeks after the tops die, whether naturally or because of mowing.
  • Sound: watermelons sound like your chest not your head or your belly when thumped. Try the “Scrunch Test” – press down firmly on the melon and listen and feel for the separation of the ripe flesh inside the melon.

Cabbages are fully mature when the head is firm and the outer leaf on the head is curling back. Ignore the separate “wrapper leaves” when making this judgment. If you need to keep mature cabbage in the ground a few days longer, twist the heads to break off some of the feeder roots and limit water uptake, and they will be less likely to split.

Mature cabbage showing curled leaf on the head.
This educational photo of a split cabbage is provided by Firesign Farm

Broccoli
Select blue-green broccoli heads and harvest them before the flower buds open, but after they’ve enlarged. We press down with finger-tips and spread our fingers to see if the head is starting to loosen.

Young immature broccoli head after rain
Photo Wren Vile

Sweet Corn

Sweet corn will be ready to harvest about three weeks after the first silks appear. Corn is ready when the ears fill to the end with kernels and the silks become brown and dry. An opaque, milky juice will seep out of punctured kernels. You can use your thumbnails to cur through the husk on the side and view the kernels. Don’t make your cut on top of the ear, or the dew and rain will get in and rot the corn.

Sweet corn ears are mature when the silks die and turn brown. Photo Kathryn Simmons
Mature Sweet corn ear.

Garlic

Garlic is ready to harvest when the sixth leaf down is starting to brown on 50% of the crop. See Ron Engeland’s Growing Great Garlic. Harvesting too early means smaller bulbs (harvesting way too early means an undifferentiated bulb and lots of wrappers that then shrivel up). Harvesting too late means the bulbs may “shatter” or have an exploded look, and not store well.

Cut across hardneck garlic – airspaces around the stem show maturity

Music garlic cut open showing gaps around stem – a sign of maturity.
Photo Southern Exposure Seed Exchange
Garlic bulb cut horizontally to check maturity (good now or soon).
Photo Wren Vile

Onions

Wait until the tops fall over to harvest, then gently dig up the whole plant and dry. Leave the dry, papery outer skin on the onion for protection.

Onions curing and drying in strings. Photo by Southern Exposure Seed Exchange

Four Ranges of Cold-Hardy Crops for Harvest at Various Stages of Winter

  1. Crops to keep alive into winter to 22°-15°F (-6°C to -9°C), then harvest. Harvest and use soon: Asian greens, broccoli, cabbage, chard, lettuce, radishes. Harvest and store: beets, cabbage, carrots, celeriac, kohlrabi, winter radish (including daikon), rutabagas, turnips. Many greens and roots can survive some freezing, so it is worth experimenting to find how late you can keep crops outdoors.
  2. Hardy winter-harvest crops: cabbage (Deadon), carrots, collards, kale, leeks, parsnips, scallions, spinach. We grow our winter-harvest crops in our raised bed area, which is more accessible in winter and more suited to small quantities.
  3. Overwinter crops for spring harvests before the main season. Some crops, if kept alive through the winter, will start to grow again with the least hint of spring weather and be harvestable earlier than spring plantings. Depending on your climate, the list can include carrots, chard, chicories such as radicchio and sugarloaf, chives, collards, garlic, garlic scallions, kale, lettuce, multiplier onions (potato onions), scallions, spinach. In mild areas, peas can be fall sown for a spring crop. Sow 1″ (2.5 cm) apart to allow for extra losses.
  4. Winter hoophouse crops: The rate of growth of cold-weather crops is much faster inside a hoophouse than outdoors. The crop quality, especially with leafy greens, is superb. Plants can tolerate lower temperatures than outdoors; they have warmer soil around their roots, and the pleasant daytime conditions in which to recover. Salad greens in a hoophouse can survive nights with outdoor lows of 14°F (–10°C) without inner rowcover.

In my post Root Crops in October, I gave this list of storable crops in the order for harvesting, related to how cold they can survive.

Clear and store (in this order):

  • Sweet potatoes 50°F (10°C)
  • “White” Peruvian potatoes 32°F (0°C) approximately
  • Celeriac 20°F (°C)
  • Turnips 20°F (°C)
  • Winter radish 20°F (°C)
  • Beets 15-20°F (°C)
  • Kohlrabi, 15°F (°C)
  • Carrots 12° F (°C)
  • Parsnips 0°F (°C)

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Here are some links to a couple of good sources for more harvest information:

  1. Piedmont Master Gardeners Garden Shed Newsletter

Guidelines for Harvesting Vegetables by Pat Chadwick

A list of seven basic principles of harvesting, followed by a crop-by-crop list of almost 50 individual crops and a resource list of 18 publications (focused on the mid-Atlantic and Southeast)

  1. October Tips from Harvest to Table, by Steve Albert covers all climate zones and comes complete with a USDA Hardiness Zone Map

Prepare your garden for colder weather, plant winter crops where there is still time, harvest crops that will suffer from cold, construct low tunnels with rowcover or clear plastic to keep crops somewhat protected from wind and cold temperatures

Links to other posts by Steve Albert

How to Prepare a Winter Vegetable Garden

Predicting Frost in the Garden

Garden Tips for October


Growing for Market articles

Harvesting seeds this fall?

I have written articles for Growing for Market magazine about growing and saving seeds (August and September issues), and planting garlic (October issue).

Given the shortages of some varieties this spring, it wouldn’t surprise us if more people tried producing seeds of vegetable or flower varieties this year. Here are links to articles from the August and September magazines, covering wet and dry seed processing.

Roma tomatoes cut in half for seed extraction.
Photo Pam Dawling

Wet seed processing and saving

Wet seeds are embedded in fruit. Wet processing has four steps: scooping out the seeds or mashing the fruit, fermenting the seed pulp for several days, washing the seeds and removing the pulp and then drying the washed seeds.

Read the article “Wet seed processing and saving”

Dry seed processing and saving

Dry seeds develop in pods, husks or ears, and dry on the plant rather than inside a fruit. While you obviously want to get seeds into the hands of growers before they need to plant, and into seed catalogs before they get printed, often there is no urgency to extract the dry-seeded crops from their pods. You can wait for a slower time, or use seed cleaning as a rainy-day job.

Read the article “Dry seed processing and saving”

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Mother Earth News Fair

I have a workshop on Winter Cover Crops for Gardeners as part of the Mother Earth News Fair Online Winter Gardening Course. The Winter Gardening Course features 7 videos, each 21-44 minutes long. Mine’s 32 minutes on cover crops.

You can enroll for the 8-course Winter Gardening Course for $20.

Or choose the 2020 all-access course bundle of 21 courses (over 100 videos) for $150.

 

 

 

 

 

 

 

 

 

 

My recent work in Growing for Market, Mother Earth News and pepper research

Seed saving and processing

August 2020 Growing for Market magazine

Heads up everyone saving seed from their tomatoes, melons, or squash this year, in anticipation of possible seed shortages next spring! Or because you have the time at home to figure out how to do it, and you’re around to stir the bucket three times a day! I have an article on wet seed processing in the August issue of Growing for Market magazine.

Roma tomatoes cut in half for seed extraction.
Photo Pam Dawling

Also see my post on washing and drying tomato seeds, with lots of photos.

The next issue will have my article on dry seed processing (think beans, peas, okra, lettuce).

The current issue also has a couple of interesting articles on how to move step-by-step towards no-till growing, or at least minimum-till. Many gardeners and farmers have floundered while making this transition, so learn from the experienced! And there’s an article by Julia Shanks on balance sheets, for those intending to make a living farming.


Winter Cover Crops for Gardeners

A no-till cover crop mix of winter rye, hairy vetch, Austrian winter peas and crimson clover.
Photo Bridget Aleshire

I have a workshop on Winter Cover Crops for Gardeners as part of the Mother Earth News Fair Online Winter Gardening Course. The Winter Gardening Course features 7 videos, each 21-44 minutes long. Mine’s 32 minutes on cover crops.

You can enroll for the 8-course Winter Gardening Course for $20.

Or choose the 2020 all-access course bundle of 21 courses (over 100 videos) for $150.

Or before summer is over, go for the $120, 8 course (56 videos) Summer Bundle.

——————————————-

What went wrong with our hoophouse peppers in 2020?

Diseased hoophouse pepper plant.
Photo Pam Dawling

Our 2020 hoophouse peppers were stunted, crinkled, yellowing and failed to thrive.

Possibilities:

  1. Too cold in edge bed A (drafts under baseboard)?
  2. Too wet in bed A (rainwater under baseboard, not much drying out due to shade of tomatoes)?
  3. Nutsedge poisoning: roots exude something that inhibits other plants?
  4. Soil too salty?
  5. Soil nutrients poor?
  6. Aphids
  7. Aphids spread a virus? (plants were crinkled)
  8. Are we sowing hoophouse peppers too early? In cells that are too big?
  9. Are we transplanting hoophouse peppers too early? Keeping them in in cells that are too small?

Possible solutions

  1. Be sure to block drafts all winter. Try not to plant peppers in cold edge beds.
  2. Close one row of driptape if soil in edge bed A seems excessively wet compared to other beds. Re-dig outside moat to keep soil water out.
  3. Do better about weeding out nutsedge. Investigate soil properties that encourage nutsedge.
  4. Use beds C and E instead of middle bed D when doing salt water wash down. Poke out holes in sprinkler, ensure all are working. Get a better sprinkler.
  5. Do soil tests in October and remediate soil as needed.
  6. We could monitor for pests and act promptly
  7. Deal with aphids and avoid viral diseases
  8. Sow later, in smaller cells.
  9. Transplant later, after potting up to bigger cells or pots.

Summary of ideas after our meeting and reading 2020 records:

  • Use fresh seed
  • Go back to deep 6 cells for sowing, (smaller than R38)
  • Use more appropriately warm growing conditions. Peppers don’t recover well from setbacks. They remain stunted long term.
  • Test soil and act accordingly.
  • Ensure salt wash-down reaches the edge beds.
  • If planting in chilly edge beds, ensure the baseboards are not drafty.
  • Don’t overwater.
  • Remove nutsedge whenever we see it
  • Monitor for pests; deal with aphids to avoid long-term virus diseases.
Pepper plant with aphids. Photo Pam Dawling

Hoophouse Pepper Records Research

  • We have been sowing 2/3 for a 4/7 transplant date. That’s maybe too long. 9 weeks.
  • 2/3/20 Hphs peppers sown as scheduled. Used R38s rather than usual deep 6s. It’s recommended not to sow peppers in large cells – they are slow growing, and it’s hard to get the watering right in large cells.
  • 2/11 -2/14 Peppers germinated. We had some trouble with keeping the germinating chambers up to temperature because we didn’t have the right lightbulbs.
  • 2/15 – 2/17 Heat mats not all plugged in or working right.
  • 2/21 resowed Gilboa. PeaceWork was old seed, poor vigor? Or low germ rate?
  • 2/28 Gilboa resows had been in tent but weren’t actually germinated. Back in fridge.
  • 3/4 – 3/9 Potted up. Is this true? R38s don’t normally get potted up. Maybe due to patchy germination?
  • 3/16 In ghs drafty zone
  • 4/5 Ghs door left open all night
  • 4/12 Ghs door left open all night again.
Hoophouse peppers in a better year!
Photo Pam Dawling

Info from Sustainable Market Farming  and The Year-Round Hoophouse

  • Sow 8-10 weeks before you intend to transplant.
  • We used to sow our hoophouse peppers 1/17, then 1/24, then 1/31, then 2/3.
  • Minimum temperature for germination is 60F, optimum 68-95F.
  • Peppers seem to produce stockier plants if soil temperatures are 65-68F, max 80F daytime, min 60F at night after germination. Use a soil thermometer.
  • Transplants getting slightly cooler nights will grow sturdier plants that flower later and have more potential for big yields. Rowcover at night if 40F or below.
  • After third true leaf, can reduce night temp to 54F. May increase yields.
  • But, permanently stunted by conditions that are too cold.
  • Keeping them in pots or cells that are too small will set them back. If transplanting is delayed, pot up to larger size, eg tomato pots.
  • Pot up when a few true leaves appear. After that no heat mat needed.
  • We moved our transplanting date from 4/1 to 4/7 (one week after tomatoes is usual)
  • Transplant at 6-9 weeks, with 4 or 5 true leaves, not yet flowering. OK if they are big.
  • Soil for transplanting should be at least 60F, ideally 68F
  • Avoid transplant shock. Soil needs to be damp before, during and after transplanting. Avoid root damage or bending. Shade if hot, sunny or breezy.
  • For the first week after transplanting, keep warm.
  • Established peppers benefit from 70-75F days, 64-68F nights
  • Maintain sufficient levels of boron, calcium, phosphorus.
  • Monitor and control aphids and thrips to prevent the diseases they vector.
  • An inch of water per week is about right.
  • Foliar feeding with fish or seaweed emulsion once a week after fruit set.
  • 65-80 days from transplant to full-size immature fruits, and another 2-4 weeks to ripe fruit.
  • Yields should be 5-18 lbs/10ft.

Ideas after rereading those sources

  • We might do better to set the sowing date a week later (2/10), keep the transplant date at 4/7 and aim for an 8 week-old transplant? (Avoid colder conditions)
  • We need to pay more attention to temperatures of germination, seedlings and potted transplants. Write the goal temperatures on the Seedlings Schedule
  • We need to pay more attention to not overwatering seedlings. Write that on the Seedlings Schedule too.

Cover Crops in Summer

 

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

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

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

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

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

Advantages of Summer Cover Crops

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

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

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

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

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

Overcoming the Challenges of Summer Cover Crops

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

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

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

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

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

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

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

Working with the time you have left.

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

Five Easy Summer Cover Crops that Die with the Frost

Buckwheat

Buckwheat cover crop in flower.
Photo Pam Dawling

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

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

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

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

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

See my post and article about buckwheat here.

Sorghum-Sudangrass

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

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

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

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

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

Soybeans

Soybeans as a cover crop
Photo agcrops.osu.edu

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

Southern Peas

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

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

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

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

Sunn Hemp

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

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

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

Late Summer Cover Crops for Winter: Oats and Barley

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

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

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

Cover Crop Resources

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

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

Forget Miami peas; Forget industrial hemp; Optimize your Asian greens

Forget Miami peas

For years I have been mentioning “Miami Peas” in my presentations about cover crops. At the Carolina Farm Stewardship conference I was asked what they are, by Mark Schonbeck, who knows cover crops well. (This is one of the wonderful benefits of attending conferences – meeting peers and mentors, and learning new things.)
I said it is a frost tender cover crop pea of the field pea type (not a southern pea). I can’t remember where I first heard about this cover crop, and we haven’t been using it on our farm, so it was time for a reality check when I got home. I can’t find any reference to Miami peas apart from the ones I’ve made! I believe it’s a type of Canadian field pea, but maybe it no longer goes by the Miami name, or maybe it never did! It’s embarrassing to promote untruths.
Spring forage peas from Seven Springs Farm, Virginia

Pinetree Seeds says:

This short term green manure smothers weeds well and adds nitrogen and other nutrients to the soil. Peas are often mixed with vetch, oats, or rye as an effective cover crop. The sprouts are delicious and you can even harvest the peas themselves for soup. This annual prefers cool well drained soil and has no frost tolerance. Sow 3 to 4 lbs per 1000 sq. ft.

For clarity, here’s what I now believe:
  • “Forage pea” and “Field pea” are terms that include the  hardy Austrian winter peas, that we do use and are big fans of, as well as frost-tender spring peas, also known as Canadian field peas.
  • Canadian field peas are not frost tolerant and are sold by Pinetree Seeds. among others.
  • SARE lists Canadian field peas as Spring Peas. SARE is a very reliable source of information. They say

These annual “spring peas” can outgrow spring-planted winter peas. They often are seeded with triticale or another small grain. Spring peas have larger seeds, so there are fewer seeds per pound and seeding rates are higher, about 100 to 160 lb./A. However, spring pea seed is a bit less expensive than Austrian winter pea seed. TRAPPER is the most common Canadian field pea cultivar.

  • Other spring pea varieties are Dundale and Arvika
  • There’s also a tropical Pigeon Pea, Cajanus cajan, which can grow in the Southern US, but that looks pretty different, and I don’t think that’s what I meant.
Pigeon Pea flowers, Cajanus cajan
Photo Wikipedia

 

Forget industrial hemp

I have been alarmed at how many small-scale growers are trying industrial hemp. Partly I’m hoping it won’t cause a shortage in locally grown food! I also wonder how well an industrial field crop grows on a small scale, and how the growers would deal with the permits, the processing and the marketing.

Read this report from The Modern Farmer about how industrial hemp is unsuccessful for most growers and how the market is swamped with would-be suppliers:

Thousands Began Farming Hemp This Year. It Hasn’t Gone How They Hoped.

Optimize your Asian greens production

Here’s my updated slideshow on Asian greens, which I presented at the Carolina Farm Stewardship conference. 

Check their website for details about other workshop sessions too. I believe my handouts, and those of other speakers, will soon be available on their website.

Click the diagonal arrow symbol to view this full screen., and click the forward arrow to start viewing.

Senposai is our star of Asian greens. Here’s a bed of senposai outdoors in spring.
Photo Kathryn Simmons