Cover Crops for September: wheat and crimson clover

Crimson clover is a beautiful and useful cover crop.
Photo Kathryn Simmons

Note: the day after I posted this I found I was mistaken in believing barley to die at a warmer temperature than oats, so I’ve edited it.

Focus Cover Crops for September: Winter Wheat and Crimson Clover

In August I wrote about cover crops such as millets, southern peas, buckwheat which are frost-killed. If it’s still too early to sow your winter cover crops, sow summer cover crops. Before I get to the wheat and crimson clover, I’ll mention some other useful seasonal cover crops.

Winter-killed, not frost-killed, cover crops

There are also cover crops that are not frost-killed, but die later in the winter, at colder temperatures, such as oats and barley. Only sow oats or barley if you are sure you can get them turned under or killed by cold winter weather before they seed. They will not mow-kill, so if the weather doesn’t kill them, you will have to turn them under. Be careful buying feed-grade seeds (rather than Organic seed-grade), as they can contain weed seeds including GMO canola.

Late corn undersown with oats, now mowed high, and the sweet potato patch now sown in winter wheat and crimson clover.
Credit Ezra Freeman

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 14-20, the cut-off date for oats is September 7, or September 15 if we really push it. Sowing too late means you don’t get enough growth in the fall, and the soil is not adequately protected from erosion or from weed growth.

We sow oats after growing early sweet corn, spring broccoli, spring-planted potatoes, cabbage, kale, or early season spinach, lettuce, beets, carrots. Spring oats die after three nights at 20°F (-7°C), or a single plummet to 6°F (-17°C), leaving the plot quick to prepare for early crops next year. Winter oats are hardier, but my goal with growing oats is for them to die in winter. 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.

Don’t let your cover crop barley go to seed! Photo USDA

Fall-sown barley (Hordeum vulgare), grows even faster than oats, but not as quickly as winter rye, and it won’t die as early in the winter as oats. Barley dies at 17°F (-8°C). It usually will die in Zone 7 and colder regions. The dead barley residue protects the soil through the winter, and dries into what Barbara Pleasant calls “a plant-through mulch” in spring in cold zones.

See Planning Winter Cover Crops, a post that includes my Short Simple Guide to Winter Cover Crops and my slideshow Cover Crops for Vegetable Growers. Oats, barley, wheat and rye sown too early can head up and seed before you get to winter, making them less useful, and more of a weed problem.

Winter-hardy grass cover crops to sow in September

It is too late for us to usefully sow cover crops that are not frost-hardy, as they won’t make enough growth before getting killed.

Winter rye and winter wheat are two grass cover crops that can be sown in the mid-Atlantic in September. Wheat is easier to incorporate than rye and has less of an allelopathic effect on small seeds, the inhibition of germination that lasts three weeks after rye is turned under. It’s true wheat doesn’t produce as much biomass as rye, so there’s the tradeoff. We sow wheat if the area is ready for cover crops 20-40 days before frost. This allows us to make faster use of those plots in the spring, compared to plots sown to rye.

Winter wheat
Photo USDA

For us wheat is a good, trouble-free winter cover crop. Winter wheat prevents erosion, suppresses weeds, scavenges excess nutrients, adds organic matter, encourages helpful soil microorganisms, and the fine root system improves the tilth. It is less likely than barley or rye to become a weed; easier to kill than barley or rye; cheaper than rye; easier to manage in spring than rye (less bulk, slower to go to seed); tolerates poorly drained, heavier soils better than barley or oats. If you have leftover seed, wheat can be sown in spring – it will not head up, but “wimps out” when the weather gets hot.

The challenges of wheat are that it does not have good tolerance of flooding, and is a little more susceptible than rye or oats to insects and disease.

Secondary cover crops in September:  Include legumes where possible

With careful planning, you can grow next year’s fertilizer for your later spring-planted vegetables! Legumes grow nitrogen-fixing bacteria on their roots, which can feed the next food crop. You may need to buy a suitable inoculant if you are introducing a new legume species. You may decide to inoculate anyway, for insurance, even if that type of legume is already somewhere in your garden. Before sowing the legume seed, dampen it, sprinkle the inoculant over the seed at a “pepper on your dinner” rate, and stir it in. Then sow the seed. Be sure not to make the seed wetter than slightly damp, or you’ll need to spread it out to dry a bit before you sow.

Two other key parts of being successful are to sow the legume early enough to establish before winter halts growth, and to plan not to need that plot next year until flowering time for that legume. At flowering time, legumes have the maximum amount of the nitrogen nodules they will have. Don’t let the legume flowers set seed, or they may become a weed problem. Take notes on when various legumes flower. 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, and won’t be able to supply all the N needs of the following food crop.

September (40-60 days before frost) is a good time to sow clovers here, provided you can supply enough overhead irrigation. They will make some growth in our climate before winter, and then a lot more once spring arrives.

Crimson clover cover crop with bumblebees.
Photo Bridget Aleshire

Crimson clover is a good September choice, if you won’t need to prepare the area before it flowers (in central Virginia 4/16-5/2, most usually around 4/20).

For a cover crop to survive the winter, sow winter wheat with Austrian winter peas, crimson clover, hairy vetch, red clover, white clover or 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.

Clover for green fallow in early September

See August’s post for info on planting a Green fallow plot (Full year cover crops)

Time is running out on this for us, but you may still have enough warm weather where you are. A green fallow crop (all-year cover crop) will replenish the soil and reduce annual weeds for the following year. In late August, or early September, four weeks after transplanting your fall brassicas, especially cabbage and broccoli, but also kale and collards, broadcast a mix of clovers: 1 oz (30 g) Crimson clover, 1 oz (30 g) Ladino white clover and 2 oz (60 g) Medium red clover per 100 sq ft (9 m2). Crimson clover is a winter annual and will be the biggest and the first to flower, in April. Medium red clover is a biennial and will be the next to flower. White clover is perennial and will take over the plot as the others subside. Be sure to get the medium red clover, not the Mammoth kind that dies when mowed. Likewise, for maximum benefit, get the tall Ladino white clover, not the low-growing “wild” type. In March, mow down the old brassica stumps and let the clovers flourish. You will be mowing this patch about once a month from March to October next year to prevent the crimson clover and the annual weeds from seeding.

Cover crops to sow soon after your first frost date

I’ll say more about this next month, and because I want this website to be useful to a geographically wide range of growers, I’m including a preview here. If the area is ready for cover crops up to 10 days past the frost date, sow winter wheat or winter rye with 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. Sow winter rye from 14 days before to 28 days after first fall frost. See Working with the time you have left in the Summer Cover Crops post. Austrian winter peas can be sown later than other legumes, it’s too late for clovers.

My book Sustainable Market Farming has a chapter on cover crops and many 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.

Mother Earth News Fair, Local Food Hub, other events

10646717_696746683734934_2365867868579925687_nI got home last night from a wonderful Mother Earth News Fair in Seven Springs Pennsylvania. I heard it was a record-breaker in attendance. It’ll probably be a week before we know for sure. I gave two of my traditional favorite workshops, Succession Planting for Continuous Vegetable Harvests and Crop Planning for Sustainable Vegetable Production. They are on SlideShare, with most of my other sustainable farming slide shows, and I’m inserting them here for new readers.We ran out of handouts at the Succession Planting workshop, but the MENF staff made more, so I hope everyone who wanted one got one.


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On Thursday 9/29 I will be offering a new two hour workshop on Cover Crops for Vegetable Growers with the Local Food Hub. 4-6 pm in Room 246,  Albemarle County Office Building, 401 McIntire Road, Charlottesville, VA. COST: $10; free for Local Food Hub partner farms. Still some seats available, as of Tuesday morning. QUESTIONS? Email Adrianna Vargo, Director of Grower Services, at adrianna@localfoodhub.org.

Crimson clover cover crop Photo by Bridget Aleshire
Crimson clover cover crop
Photo by Bridget Aleshire

imagesOn Saturday 10/1 I will be at Lynchburg College, 1501 Lakeside Dr, Lynchburg, VA 24501 (SW Virginia) with Ira Wallace of Southern Exposure Seed Exchange, co-presenting The Seed Garden: Planning for Seed Saving and Lots of Vegetables. That’s 10.00 am to 12.30 pm. My contribution will be to talk about including a few seed crops while mainly focusing on producing vegetables. We’ll have show and tell as well as slides.


I have started an Events Page here on my website, but while I keep running from one event to another, I’m not spending the time to make it pretty. Hopefully next week. For those in Vermont – you will be getting your own Vermont Mother Earth News Fair in July 2017, and I hope to see you there!


 

Below is info on an interesting symposium for those doing urban agriculture.

Urban Agriculture Symposium

VIRGINIA COOPERATIVE EXTENSION, ARLINGTON COUNTY OFFICE

Fairlington Community Center, 3308 S. Stafford St., Arlington VA 22206

Telephone 703-228-6400

Contact:  Kirsten Buhls, Agriculture and Natural Resources Extension Agent kbuhls@vt.edu

The 2016 VCE Urban Agriculture Symposium will be held on Saturday, Oct. 1, from 8:30 a.m. to 3:30 p.m. at Fairlington Community Center, 3308 S. Stafford St., Arlington 22206. The symposium is being held in conjunction with Urban Agriculture Month in Virginia and is sponsored by VCE and Greenstreet Garden Center in partnership with Master Gardeners of Northern Virginia.

The keynote speaker will be Carlin Rafie, assistant professor at Virginia Tech and VCE adult nutrition specialist, who will discuss the relationship between nutrition and health.  In breakout sessions, Virginia Tech researchers and other experts will focus on perennial and tree crops for the urban gardener; research on growing food with biosolids; growing nutritious, low-maintenance vegetables; small-space gardening of the future; aeroponic containerized farming; teaching the next generation of gardeners; and growing microgreens and sprouts at home for winter nutrition.

Registration is open to all. The fee is $25 and covers the cost of supplies as well as refreshments and lunch for participants. More information and a registration form are available at mgnv.org; click on the link http://bit.ly/VCEUrbanAgSymposium.

Questions? Call 703-228-6414 or email mgarlalex@gmail.com.


Meanwhile in the garden, we have got lovely little kale and bigger spinach seedlings, and we are thinking about potato and sweet potato harvests in a couple of weeks.

Sweet potato harvest with carts. Usually we use a truck! Photo Nina Gentle
Sweet potato harvest with carts. Usually we use a truck! Photo Nina Gentle

Insect mesh, shadecloth, crimson clover, sowing corn, too much rain

May2016_cover_300pxThe May issue of Growing for Market is out, including my article about protecting crops in the summer, using shadecloth and insect mesh (netting).

If you want to grow lots of summer crops in buggy places, net houses (hoophouses covered with insect mesh rather than poly) may be your answer. If the bugs are not tiny, small mesh shade cloth may be an even better choice than insect mesh, because it cools while keeping the critters out. Search for project FS13-275 at http://www.southernsare.org. The document High Tunnel Pest Exclusion System: A novel strategy for organic crop production in the south is available from a link in that report.

Shade cloth on a bed of lettuce in summer. Photo Nina Gentle
Shade cloth on a bed of lettuce in summer.
Photo Nina Gentle

I write about using shade cloth for cool weather crops like lettuce during the summer, and also about research into the improvements to yields of peppers when using shadecloth. 30% shade cloth can increase pepper yields by 100% (yes, double the yield!). See the University of Georgia paper Shading helps south Georgia pepper farmers beat the heat. For hot weather lettuce, we use 45-60% shade cloth on spring hoops 6-8 feet apart, with a plastic clothespin to attach it at each hoop.  Shadecloth lets air through better than row cover does, so it’s less likely to blow away. We don’t use any weight to hold the edges down. We keep the shade cloth on for 2-3 weeks after transplanting, then move it on to the next planting, in a single operation. 2 or 3 people pull up the hoops with the shade cloth still attached, and parade it like a Chinese dragon procession.We cover our hoophouse from mid-May to mid-September with shadecloth. Photo Kathryn Simmons

We cover our hoophouse from mid-May to mid-September with shadecloth.
Photo Kathryn Simmons

Rowcover (white polypro or polyester non-woven fabric) is often used by growers in cold weather to extend the season. There are also lightweight rowcovers for insect exclusion. These can be fragile, and holey row cover doesn’t keep insects out! We switched to only buying thick rowcover and use it  for some crops even in summer. It doesn’t heat up as much as people fear. Johnnys Seeds has a helpful row cover comparison chart

ProtekNet over kale transplants in August. Photo by Bridget Aleshire
ProtekNet over kale transplants in August.
Photo by Bridget Aleshire

But even better for protecting plants against bugs in summer is ProtekNet, a translucent polyamide (nylon) fabric which comes in different mesh sizes. it allows better airflow than rowcover, and better light permeability (from the plants’ perspective) – visibility from the human perspective. Dubois offers free shipping on online orders over $200. ProtekNet is also available from Purple Mountain Organics in Maryland, and  Johnnys Seeds in Maine.


Also in this issue of Growing for Market Jane Tanner writes about the benefits of no-till farming, in building topsoil, encouraging soil micro-organisms and reducing weed pressure.  She writes about several farms, all following the model of small acreage, intensively farmed, mostly with manual tools. This system, advocated by Jean-Martin Fortier in The Market Gardener, includes “occultation”, the practice of covering damp soil with heavy black plastic for several weeks to kill weeds. This article includes photos of occultation and a clear explanation. Cover crops are another important feature of this system. I found this a particularly information-packed article, one I will return to.

9221576_origKarin Tifft writes about IPM tools (Integrated Pest Management) for small and organic farms, making the topic accessible to those of us with only a short amount of reading time! We can read enough now to make some actual differences to our pest levels. Later we’ll want to read more, as results pile up.

Nikki Warner writes with advice for managing a farmers market, and Ralph Thurston and Jeriann Sabin write about starting a flower farm (Excerpted  from their book Deadhead: The Bindweed Way to Grow Flowers with their permission.)


We sowed our first corn on Thursday. the soil temperature was 60F, so we were OK on that score. But then it rained and rained. The soil is saturated. I wonder if the corn seed will rot in the ground? Also the bean we sowed last week. Was I too hasty? We’ll see.


Meanwhile, a cheery sight has been the flowering crimson clover cover crop

Crimson clover cover crop Photo by Bridget Aleshire
Crimson clover cover crop
Photo by Bridget Aleshire

This patch is where our fall broccoli was last year. We under-sowed with a mix of crimson clover, Ladino white clover and medium red clover. If you look closely you can see the white patterned leaves of the red clover and the tiny leaves of the white clover in the understory. Also the seeding chickweed, which will disappear as soon as we bush hog the patch. Our goal here is to maintain the clovers all year, adding nitrogen to the soil for next year’s food crop and swamping the weeds. We’ll mow every time it looks weedy.

Winter rye and crimson clover cover crop Photo by McCune Porter
Winter rye and crimson clover cover crop
Photo by McCune Porter

In this second picture, you can see a patch where we sowed winter rye mixed with crimson clover in late October as a winter cover crop. In most places the rye is taller than the clover, so it’s not as overwhelmingly pretty as the first patch, but it’s packing a lot of biomass to feed the soil. It will get disked in soon (when the soil dries enough!), in preparation for later sweet corn sowings.

Corn planting time!

Last year's young sweet corn plants with a fiber banana plant to the right. Credit Bridget Aleshire
Last year’s young sweet corn plants with a fiber banana plant and a sunflower to the left.
Credit Bridget Aleshire

A week ago, I showed a group of local Master Gardeners around our gardens. At that point, the raised bed area was a mixed portrait of rowcover and weeds! All the crops were sheltered under cover and all the visible beds were full of weeds. So much has changed in a week. We mowed all the weedy beds, tilled many of them, and removed the rowcover to our strawberry beds and our new cabbage and broccoli planting. We’ve even found time to hoe the planted beds and weed and thin the three beds of beets.

We had more struggles with our broccoli.  A couple of weeks ago, I told you all about the moles gathering nesting material from our first broccoli flats. We dealt with that, planted out what we had left, and moved our second planting to the coldframe. Something browsed on them. Deer? Rabbits? Groundhogs? We sprayed the plants with a stinky deer repellant and scattered hot pepper on them. And covered them at night. Now we’ve planted those out and put the third planting in the cold frame. So far, so good. . .

The black center of this strawberry flower show that it was hit by frost and no berry will develop. Credit Kathryn Simmons
The black center of this strawberry flower show that it was hit by frost and no berry will develop.
Credit Kathryn Simmons

We’ve had a couple of cold nights (hence the need to move the rowcover to the strawberries to protect the blossoms from possible frosts.)

Healthy unfrosted strawberry flower. Credit Kathryn Simmons
Healthy unfrosted strawberry flower.
Credit Kathryn Simmons

But overall the season is warming up. After lots of waiting we are finally getting asparagus. Many of the signs of spring all happened in rapid succession: the lilac is blooming, morning glories and smartweed have germinated, the crimson clover cover crop is starting to flower and I’ve heard the whippoorwills at night.

Crimson clover is a beautiful and useful cover crop. Credit Kathryn Simmons
Crimson clover is a beautiful and useful cover crop.
Credit Kathryn Simmons

The white oak leaves have definitely exceeded the size of squirrels’ ears. This is our sign to sow sweet corn. We did that yesterday. Bodacious, 77-days to maturity, yellow, great flavor for corn this early. These days we hedge our bets and also extend the harvest period by sowing the second half of the patch 3 days after the first half. Contrary to myths you might have heard, it is quite possible to transplant sweet corn, so those in marginal climates don’t need to give up hope. We usually prepare some plugs the same day we sow our first corn outdoors and use these to fill gaps at the first cultivation.  If disaster doesn’t strike and there are no gaps worth worrying about, we give the transplants away to local gardeners who were less lucky, or didn’t get round to direct sowing their own.

We use 200-cell Styrofoam Speedling flats (1″, 2.5 cm cells) with one corn kernel in each cell. We float them in a tank of water until we set them out. Some vegetable seedlings would drown if continuously in water, but corn does not. It is important to transplant the corn before the plant gets too big and the taproot takes off. Two- to three-inch (5–7.5-cm) plants seem OK. The plugs transplant easily using butter knives.

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

Here’s an aspect of hybrid corn varieties that confuses many people: There are several genotypes, and if you inadvertently plant a mixture of different types, it can lead to starchy unpleasant-flavored corn. Ignore those cryptic catalog notes at your peril! here’s the Cliff Notes:

Normal sugary (su or ns) types have old-fashioned corn flavor but are sweeter than open pollinated varieties, although the sweetness disappears fairly rapidly after harvest. Not a problem for home gardeners who can cook the corn they harvested earlier that day. Most can germinate well in cool soil. 

Sugary-enhanced (se) and sugary enhanced homozygous (se+ or se-se) types are more tender than (su), and slower to become starchy after harvest. Most, especially the (se+) types, are sweeter than (su) types. We grow (se) and (su) types, and avoid the others – sweetness and simplicity!

Nearly all newer sweet corn types rely on one of two recessive genes, su or sh2. Cross-pollination with other corn groups will produce the dominant genetics of field corn, that is, starch not sugar. Don’t mix Super Sweet sh2 types with any other corn. Also don’t plant Indian corn, popcorn or any kind of flint or dent corn within  600′ (180 m) of your sweet corn. For this reason we grow only sweet corn in our garden. In case you are tempted by variety descriptions of the newer types, though, here’s more about them:

The Super Sweet (sh2) varieties, also known as shrunken, are very sweet and slow to become starchy. They have very poor cold soil germination. The kernels are smaller than other corns, giving this type its name.

Synergistic (se-se-se-sh2) types are combinations of genetics from several genotypes. Each ear has 75 percent (se) kernels and 25 percent (sh2) kernels. They are flavorful, tender and sweet, but only when they are ripe. If picked too soon, they are a watery disappointment. 

“Augmented shrunken” types contain the sh2 gene and some of the tenderness from the se types. 

We’re looking forward to plenty of sweet corn this year – we’re off to a good start!