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Summer Cover Crops

Cover cropping is an incredibly beneficial practice for anyone who gardens. It helps improve the soil, protect the environment, attract pollinators, and so much more. Unfortunately, most gardeners think of cover cropping as a practice for the off season. However, summer cover crops have a lot of unique benefits and you can work them into your garden without giving up any production. 

Benefits of Summer Cover Crops

Summer cover crops can help improve your soil health and production during the season. They also help protect your garden and the environment in several essential ways.

Reduce erosion. Usually associated with fall and winter storms, erosion isn’t a major focus in summer, but it can happen any time of year. It’s a critical issue in the United States. Scientists estimate that we’ve lost 30% of our topsoil in the past 200 years. 

In summer, all it takes is a strong thunderstorm rolling through to wash away loose soil or drying winds picking up soil particles. You should never leave your soil bare. 

Erosion doesn’t just negatively affect your garden health, it has significant impacts on the ecosystem. Eroded sediment and nutrients end up in streams, rivers, and eventually the ocean, where they can cloud waters and cause toxic algae blooms.

Having cover crops on the soil also allows for better water infiltration and soil structure which can help you create a more drought resistant garden. 

Suppress weeds. Weeds are at their most aggressive in summer, which is why it’s a key time to get ahead of them with cover crops. Quick growing cover crops can crowd out and shade weeds, suppressing them for later vegetable crops. 

Some cover crops like buckwheat and sorghum sudangrass also release chemicals to prevent the germination or growth of weed in a phenomenon called allelopathy.

You can also kill the cover crops through rolling or mulching and leave them on the surface as mulch. Then transplant crops into the mulched bed. The mulch will continue suppressing weeds as it breaks down.

Attract beneficial wildlife and insects. Beneficial animals and insects are some of the gardener’s best allies. Some like hummingbirds, flies, bees, and butterflies pollinate crops. Others like swallows, bluebirds, toads, wasps, lady beetles, lacewings, and wheel bugs feed on common garden pests, keeping their populations low. A few, like earthworms, millipedes, and pill bugs, help break down organic matter, improving soil structure. 

None of these animals or insects thrive in areas with bare soil. Sowing cover crops provides cover and food sources. Some cover crops like buckwheat and hairy vetch also have flowers that may help attract predatory wasps, bees, and other pollinators. 

Fix nitrogen. Certain cover crops are nitrogen fixers. These plants have a symbiotic relationship with specific bacteria. The bacteria colonize the plant’s roots and pull nitrogen out of the atmosphere. The bacteria use the nitrogen and then it becomes available to the plant.

These nitrogen-fixing plants include a few summer cover crops like southern peas, soybeans, buckwheat, sunn hemp, and hairy vetch. 

To make the nitrogen available to your next crop, the cover crop needs to die and decompose. Depending on the crop, you can kill it by cutting it, tilling it under, tarping it, or waiting for frost to kill it in the fall.

Add organic matter. Fast-growing summer cover crops are a great way to add tons of biomass to the soil. As they break down, they add organic matter, which improves soil structure, increases water infiltration, provides nutrients, and increases microbial and beneficial insect activity. 

Impact plant diseases. In some cases, summer cover crops may help disrupt disease cycles in the garden. Some research has shown reductions in blight in no-till, cover crop gardens. Pearl Millet Summer Cover Crop

How to Work Summer Cover Crops into Your Garden Plan

You don’t need to give up production to grow summer cover crops! There are several ways you can squeeze cover crops into the summer garden without sacrificing your vegetables.

Use pathways. If your garden has pathway space, you can take advantage of it by sowing it in a cover crop like white clover which will tolerate some traffic. You can mow the paths and apply it as mulch under other crops.

Interplant. You can also interplant cover crops. Strips of clover, vetch, and other cover crop can have amazing benefits. According to the North Carolina State Extension, “research in Georgia reported high densities of big-eyed bugs, lady bugs, and other beneficial insects in vetches and clovers.” They also found that, “assassin bugs have destroyed Colorado Potato Beetle feeding on eggplant planted into strip-tilled crimson clover.”

You can grow some cover crops in between other crops. Plant soy beans or southern peas beneath tall crops like corn or sunflowers. You can also grow fast-growing cover crops like buckwheat between hills of vining crops like winter squash or melons. Cut the buckwheat as the vine start to sprawl and use it as mulch. 

Pull unproductive crops immediately. If your lettuce has bolted, radishes have gone woody, or beans are slowing down, consider pulling them and sowing a summer cover crop. While letting lettuce flower and beans decompose naturally may provide some minor benefits, using a cover crop is a more productive use of the space. 

Beat the heat. In the Deep South, the hottest days of summer can limit vegetable production. Rather than fighting the heat to eek out more production, you may just want to avoid it. For some crops like brassicas, greens, bush beans, and cucumbers, you can get plenty of production in the early summer and fall.

Take well-earned breaks. If you find your garden is getting away from you and your summer is busier than expected, it may be worth sowing a cover crop rather than another succession. A cover crop will essentially take care of its self while improving your soil for another crop in the fall or next season. Sometimes this is more productive than sowing more beans, squash, or other vegetables you won’t have the time to weed, harvest, and preserve.

Buckwheat spring cover crops in bloom

How to Select a Summer Cover Crop

All summer cover crops have their pros and cons. What cover crop you should choose will be based on a few factors:

  • Time Available
    It’s easiest to choose and appropriate cover crop when you have a good garden plan. Maybe you want a heat tolerant cover crop to grow for 30 days in the middle of summer in between squash plantings. Buckwheat may work in this scenario. Maybe you have an empty bed 80 days before your first frost and want a cover crop that will die back and allow you to plant fall garlic. Sunn Hemp could be a good choice.
  • Frost Tolerance
    Some summer cover crops like buckwheat, are frost sensitive and will die with the first frost in fall. Others, like clover and oats, will continue to grow.
  • Nitrogen Fixation
    If your next crop is a heavy feeder like broccoli, corn, garlic, onions, or tomatoes, choosing a nitrogen fixer like sunn hemp, hairy vetch, clover, soy beans, or southern peas is a great option.
  • Biomass Production
    If adding organic matter to the soil is a priority, you’ll want to choose a cover crop that quickly puts on a lot of biomass. One of the best options is sunn hemp which can reach 6 feet tall in 60 days. Other good options include buckwheat, millet, sorghum sudangrass, vetch, oats, and barley.

Here are a few summer cover crops you may consider. Listed with each are some of their important features. 

Buckwheat

  • Blooms and is ready for incorporation in 30 to 45 days.
  • Fast growing.
  • Frost sensitive.  
  • Flowers attract bees and parasitic wasps. 
  • Tender stems are easy to cut down.
  • Deep root system is adept at mining subsurface minerals.

Pearl Millet

  • Ready for incorporation in 40 to 60 days.
  • Grows well in acidic soil and poor soil.
  • Thrives in warm climates.
  • Drought tolerant.
  • Excellent biomass producer growing 3 to 6 feet.
  • Frost sensitive.

Sunn Hemp

  • Ready for incorporation in 60 to 90 days.
  • Fast growing and excellent producer of organic matter (may reach 6 feet).
  • Nitrogen fixing.
  • Frost sensitive.
  • Suppresses nematodes.
  • Thrives in hot climates.
  • Tolerates drought.
  • Extract nutrients from deep within subsoil. 

Soy Beans

  • Ready for incorporation in 45 to 60 days.
  • Fast growing. 
  • Tolerates hot weather.
  • Nitrogen fixing.

Southern Peas

  • Ready for incorporation in 50 to 60 days.
  • Vigorous.
  • Drought tolerant.
  • Nitrogen fixing.
  • Sprawling vines.

Sorghum Sudangrass

  • Ready for incorporation in 60-70 days.
  • Suppresses weeds.
  • Suppresses nematodes.
  • Loosens subsoil and reduces compaction.
  • Excellent biomass producer growing 5 to 12 feet tall.
  • Provides habitat for beneficial insects like lacewings.
  • Requires a large mower and is tough to cut with hand tools. 

Oats 

  • Ideal for late summer and early fall planting.
  • Grows quickly.
  • Produces plenty of biomass or mulch.
  • Frost hardy.
  • Oats will get winter-killed when temperatures drop below 10°F.
  • In cold climates, it makes an excellent mulch for spring crops and in arm climates you can cut it in spring.

Barley

  • Ideal for late summer and early fall planting.
  • Frost hardy.
  • Drought tolerant. 
  • Barley will get winter-killed when temperatures drop below 17°F.
  • In cold climates, it makes an excellent mulch for spring crops and in warm climates you can cut it in spring.

Hairy Vetch

  • Ideal sowing period from August 1st to November 1st. 
  • Highly efficient as a nitrogen fixer, it’s recommended to wait until at least 50% of the plants have flowered before mowing the crop to maximize nitrogen fixation. 
  • In the spring, after flowering starts, mow the vetch and transplant tomatoes or other large plants directly into it, or till it under.

Clover

  • Cold tolerant perennial.
  • Versatile and may be sown in winter, spring, late summer, or fall.
  • Excellent for suppressing weed growth.
  • Nitrogen fixing. 
  • Attracts beneficial insects.
  • Acts as a living mulch in paths or between rows.

Creating a sustainable, productive garden means that we’re focusing on soil health year round. As you plant and plan your garden this season, think about where you may be able to sneak in a few summer cover crops. 

A Beginner’s Guide to Spring Cover Crops

Fall cover crops are a common way to build healthy soil over the off-season, but what about spring? Spring is a key time for getting vegetable crops in the ground, but it can also be a wonderful opportunity to battle the weeds and revitalize the soil before transplanting or sowing your warm season crops. While not as popular as fall cover crops, spring cover crops can be an essential tool for small farmers and gardeners. 

Why Plant Spring Cover Crops?

Cover crops have an enormous list of benefits, but it’s best to focus on just a couple of major goals when you’re selecting and planning spring cover crops.

Suppressing Weeds

Fast-growing spring cover crops are an excellent way to get a head start on the weeds. As they grow, they block out light from reaching the soil, preventing weed seed germination. Some may even out-compete annoying weeds like quack grass!

Oats or a mixture of oats and field peas are a great, quick-growing option for early spring weed suppression. As the season warms up, buckwheat is another great option for suppressing weeds, though you need to plant it after any danger of frost. 

Boosting Nitrogen

Green manure crops (those cover crops you terminate and incorporate into the soil), can be a quick way to add nitrogen and organic matter before a cash crop. Nitrogen-fixing crops like field peas, hairy vetch, or in cool areas, Austrian winter peas, are excellent options for spring green manures. 

These early spring green manures are perfect for sneaking in before summer heavy feeders like sweet corn, hot peppers, or tomatoes. 

Growing Mulch

You can also provide mulch for transplants, with a spring cover crop. Growers cut, roll, or tarp spring cover crops like oats or buckwheat, killing the plants and leaving the material on the bed. Then they transplant summer crops like eggplants or squash directly into the mulched bed. 

Resting Beds

Commercial growers and those folks with sizable gardens will often find it helpful to allow a garden or bed to have an entire season or year to “rest.” This is a great, cheap way to revitalize soil, though it affects your production capacity in the short-term. 

In areas with long seasons like the Southeast, you will probably need to plan multiple successions of cover crops. However, crops like white clover, which will grow the year through, are another popular option.

Covering Pathways & Margins

Few people like mowing, but keeping garden pathways and margins cropped is important for accessibility and weed prevention. Adding cover crops to these areas can help you make the most of your mowing. Sow a crop like white clover, then mow and use the nitrogen-rich clippings to mulch beds or build compost. 

Buckwheat spring cover crops in bloom
Buckwheat

Timing Spring Cover Crops

Understanding your timing is key to selecting an appropriate cover crop for your garden. When can you sow a cover crop? When do you need to terminate the crop? What is going into the bed next? When is your last frost and what is your climate like? These are all important considerations. 

In the Southeast, you can often sow cool-weather cover crops in late winter or very early spring provided your gardens aren’t to water-logged. There are several great cover crop options, like oats, field peas, Austrian winter peas, white clover, and hairy vetch that are fairly tolerant of cold, moist conditions, and minor frost. Look up your hardiness zone to find out your last frost date.

Some cover crops like buckwheat, cowpeas, and sunn hemp thrive in warm weather. These crops are frost sensitive, so you’ll need to sow them after all danger of frost has passed. 

Determining which crop to plant also depends on what your plans are for that bed. If you’re planning on planting that bed in late spring or summer, determine your planting date so you can terminate your cover crop a couple of weeks before that. 

You can also use the warm-season cover crops later in the summer. For example, grow a bed of lettuce in early spring. When it bolts, sow the bed with a warm season crop like buckwheat or sunn hemp. Follow with a fall crop of bush beans. 

Oats
Oats

Spring Cover Crops & Their Benefits

Once you have established your goals and timing for your cover crop, you can select the appropriate species for your garden. Here are a few spring cover crops we recommend and what they excel at:

Oats

Highly effective in cool, spring soil, oats are an excellent way to quickly add tons of organic matter to the garden. Oats mature in about 60 days. For cover crops, harvest them before they go to seed. 

Field Peas

Field peas fix nitrogen and tolerate spring’s cool temperatures well. Their sprawling nature makes them great for suppressing weeds, too. They generally mature in 50 to 75 days. Cut or incorporate after they have fully bloomed but before they set seed.

Oats and field peas are a popular spring cover crop mix. The oats provide great structural support for the nitrogen-fixing peas.

Austrian Winter Peas

These cool-weather loving peas are a great nitrogen-fixing crop for the winter or early spring garden. As a bonus, they offer edible tendrils perfect for spring salads.

In most of the Southeast, we recommend Austrian Winter Peas for fall planting. However, in cool mountainous areas or northern regions, they do well in early spring.

Hairy Vetch

Hairy vetch is another cool weather loving, nitrogen-fixing legume. It’s generally best to sow hairy vetch in the fall, between August 1st and November 1st. However, it can be spring sown, and is common in vetch, oat, and field pea mixes. 

You may cut vetch and use it as a mulch for transplanting into or till it under as a green manure.

White Clover

White clover is a perennial cover crop that’s fairly tolerant of trampling and mowing. It makes excellent lawns, borders, and pathways around vegetable gardens and its clippings can help give beds a rich boost. It’s also an excellent long-term cover crop. 

However, it’s slow to establish and not as ideal for smothering weeds. You will need to prepare the ground and keep it moist. 

Buckwheat

Buckwheat is an excellent option for weed suppression and adding organic matter. It’s incredibly fast-growing and puts on tons of mass which can act as mulch or help lighten heavy soils. It also attracts beneficial insects. 

Buckwheat readily self seeds. If you’re using it as a cover crop, cut or roll it in 30 to 40 days when it’s blooming, but before it has put on seed. 

Keep in mind that you may have different experiences in a different climate. For example, clover thrives where SESE is in the eastern United States but may struggle in arid climates.

Cover crops are a cost-effective, organic way to improve your soil in any season. Selecting appropriate spring cover crops can help you increase soil fertility, add organic matter, suppress weeds, and attract beneficial insects. Which will you be sowing this season? 

Red Clover: A Cover Crop & Herb

Red clover (Trifolium pratense) is an herbaceous biennial plant native to Europe that has naturalized throughout North America. While some consider red clover a weed, herbalists, and gardeners recognize its value. This beautiful plant is excellent for soil and human health. Here are some of the reasons we’re big fans of red clover and how we use it. 

Red Clover as a Cover Crop

Red clover is a nitrogen-fixing cover crop. It’s an excellent choice for adding green manure to build up soils and a good nectar source for some pollinators. You can sow it in fallow fields, pathways, and small openings to help suppress weeds. 

You can sow red clover in early spring, late summer, or fall as a winter cover crop. It can be a little slow to establish, so sow clovers at least 40 days before your average first frost.

Consider using buckwheat as a nurse crop if you’re sowing red clover during the hotter months. The clover will grow slowly under the buckwheat until fall frost kills the buckwheat, allowing the clover to establish quickly without the need for fall tilling.Bumblebee on a red clover blossom

Red Clover in Herbal Medicine

I’m not a doctor. This article is for informational purposes only. Consult a physician or clinical herbalist before using herbal remedies to treat any condition. 

Herbalists have used red clover for centuries to treat a wide range of conditions, from menopause to whooping cough. Many of its uses revolved around female health. Modern science is beginning to explore the properties of plants, including red clover. While further research is needed, red clover tea and tincture may have a few potential benefits.

Benefits of Red Clover

  • Red clover contains phytoestrogens, which can mimic estrogen in the body.
  • Red clover may reduce osteoarthritis symptoms related to menopause. A 2015 study of 60 women found that taking red clover extract over 12 weeks reduced bone mineral density loss in the spine.
  • In another study of 109 postmenopausal women, participants reported skin and hair texture improvements after taking red clover extract for 90 days.

Further research is needed in all of these cases. Don’t use red clover if you have a hormone-sensitive condition like breast cancer. 

Harvesting and Using Red Clover

Beyond its health benefits, red clover is also just an enjoyable herb to use. Both the leaves and the flowers are edible. Some of you may remember pulling the pink blossoms from the flowerhead and eating them as a kid. 

The leaves, which have a mild bean-like flavor, can be added to salads. The blossoms, which are sweet, can be used in tea, baked goods, or salads. It’s best to break them up or pull the tubular flowers from the flowerhead, as whole flowerheads can be dry and tough to chew.

Harvest leaves and flowers that look fresh and are free from dried, brown spots. Remember to leave some blooms for the pollinators, especially if you’re harvesting from wild patches.

Three glasses of summertime herbal iced tea with red cloverRed Clover Tea

Making red clover tea is simple: Pour about 2 cups of boiling water over about 1/4 to 1/2 cup of fresh or dried red clover blossoms and let it steep for 10 to 15 minutes. You can also let it cool and pour it over ice to make a fun summertime herbal iced tea. 

Red clover mixes well with other flavors. Feel free to experiment with adding lemon balm, mint, white clover, chamomile, or orange slices to the mix and sweeten with honey or maple syrup to taste.

Red Clover Tincture

Using the folk method, you can make a basic red clover tincture with fresh or dried red clover blossoms. All you need is a few simple ingredients and some patience. 

You simply place the blossoms in a glass jar and cover them with 80-proof alcohol. Then, keep the tincture somewhere dark for 2 to 6 weeks, shaking it once a day. After this period, you can strain it and begin using it.

Be sure to check out our complete instructions for Folk Method Tinctures.

Red clover is a fun herb to grow and use. Try growing it as a cover crop in your garden this season and enjoy its many soil health, culinary, and herbal benefits.