Why You Should be Cover Cropping Your Garden

Think of cover cropping as humans resting at night. We wake up refreshed, recharged, and ready to tackle the day after a good night’s rest. Cover crops do this for our soil, even in small gardens. 

“Cover crops have been used to improve soil and the yield of subsequent crops since antiquity. Chinese manuscripts indicate that the use of green manures is probably more than 3,000 years old. Green manures were also commonly used in ancient Greece and Rome.” (Building Soils for Better Crops)

In recent years, farmers and gardeners have once again found that cover crop use improves soil fertility, decreases weed pressure, and reduces soil compaction and erosion. In addition, crop yields will increase, and plants will thrive. 

Winter cover crops are sown in late summer or early fall to establish before winter. They remain in the ground until spring, either dormant and alive or perishing in a frost, covering the soil surface as rain, snow, and frost occur. 

Let’s discuss how beginners can start easily with cover crops, which are easy to sow, manage, and terminate as you get into the swing of things, setting you up for long-term success. 

Understanding Winter Cover Crops

Growers should sow winter cover crop seeds in the summer or fall with enough time to establish before your region’s first frost. Add this to your list of chores to complete in preparation for winter. Read, Prepare Your Garden For Winter by Completing These 8 Chores, so you don’t miss any crucial steps. Cover crops are meant to remain in the ground until the spring and may include one seed or a mix of several types. Covering your soil with the right cover crops will provide a safe and healthy haven for native pollinators and wildlife, improve soil fertility and structure, and add organic matter to your garden. 

You might wonder why using winter cover crops is essential in small gardens. Many small-scale gardeners grow intensively, working their soil for everything it’s got. While this method is commonplace and nothing is wrong with it, your soil only has so much juice, aka nutrients. Cover crops help revitalize it, add nutrients and organic matter, and reduce soil erosion caused by heavy rainfall, wind, and snow melt. Plus, your spring beds will be ready for planting. While it may seem like an additional, unnecessary step, you’ll likely see a massive difference in your garden’s productivity after just a season or two, and the benefits just increase from there. 

Winter is a time for gardeners to rest. The fantastic thing about adding cover crops to a winter garden is that your garden is still working, even though it seems dormant. There are two types of annual winter crops:

• Winter-killed: If you receive frost in your region, winter-killed cover crops will die. You’ll get the most biomass if you sow them early enough to mature before they die. Depending on the length of your season, you may only grow spring crops in an area where you want to sow winter-killed cover crops to allow them plenty of time to mature.
  The biomass will remain on the soil surface, protecting it from erosion. In the spring, growers can till or fork the plant matter, and garden beds are ready to plant into. As the debris breaks down, the soil receives fertility. Popular winter-kill cover crops are oats, field peas, oilseed radishes, and rapeseed. 

• Winter-hardy: These will survive through the winter, go dormant, and grow again in the spring. Their root systems will reduce erosion, and their presence will help suppress annual spring weeds. Winter, or cereal rye, is northern growers' most popular and hardiest winter cover crop.

Cover crop seed mixes may include a blend of the two types. The winter-killed crops will serve as mulch as the winter-hardy varieties continue to grow or go dormant for the winter, regrowing in the spring. For more info on sowing cover crops in the fall, read our article, Cover Crops For Successful Land Management | Fall Cover Cropping. 

Top 5 Beginner-Friendly Winter Cover Crops

1. Ryegrass (Lolium multiflorum)

If your region experiences harsh winters, strong winds, and heavy rainfall, ryegrass is the grass for you. It quickly produces a large stand with strong roots to help reduce soil compaction and erosion while improving the soil’s structure due to its intense root systems. 

Sow rye grass in mid to late summer in USDA Zones 1 to 5 and in the fall in USDA Zones 6+. It germinates well in full to partial sunlight and well-draining soil. Temperatures can vary from warm to cool; germination will take three to five days. To establish it as a “nurse crop” for fall crops, sow it a few weeks earlier than that crop. Nurse crops block wind, suppress weeds, and reduce disease by limiting the water splash young transplants receive. 

The term “rye” is often used as a short-term for both ryegrass and winter rye. Before planting based on farmer advice, ensure you know which is best for your garden. 

The nutrient benefits are similar in both ryegrass and winter rye. Use deep watering irrigation lines to water if your region is dry to help it establish healthy roots. 

Ryegrass is an excellent forage crop for homesteaders with goats, chickens, or sheep. Protein levels are 12 to 25%. However, animals should be allowed to forage before the ryegrass is very tall and dry to keep the risk of ryegrass staggers to a minimum. Ryegrass can host the fungus that causes this disorder, Neotyphodium lolii. While ryegrass staggers are not typically fatal, it’s something growers should be aware of and prepared for. 

Like other grasses, rye grass goes dormant in the fall, covering your soil with no extra effort. It will refresh itself in the spring, growing again. You must terminate ryegrass before seedheads form and begin to drop. In USDA Zones 5+, they’ll readily reseed, popping up all over your property in unwanted areas. 

Pro tip: When using ryegrass as a cover crop, have a plan of action before sowing it, as it can hybridize and become invasive if growers aren’t careful. 

Related: How Do Frost Blankets Help To Prevent Crop Loss?

2. Winter Wheat (Triticum aestivum L.)

Winter wheat is gaining traction among no-till farmers and small-scale growers as a trendy, easier-to-manage alternative to winter rye. It’s slow to mature, offers many benefits as most other cereal cover crops, and does an incredible job of suppressing weeds. Its slow maturity rates give growers leeway in crimping, mowing, or tilling it in the spring. Use it in pathways alongside beans or potatoes or under sow it throughout fall greens like collards, kale, and Swiss chard to give it time to establish while not impeding. 

Wheat is easy to incorporate once mowed or chopped down into the soil. The debris adds biomass and can improve soil structure. A dense sowing will ensure your wheat doesn’t winter-kill. Winter wheat tolerates poor drainage and heavier soil, but a flood could cause damage and drown wheat. And, with little to no pests and diseases, it’s the perfect crop to add to your garden’s lineup.

USDA Zones 3 to 7 growers should sow winter wheat in late summer or early fall when they remove long-season crops like peppers and tomatoes to help replenish soil following heavy feeders. Growers in Zones 8+ can wait until fall or early winter. If you miss the ideal planting window, consider rye. Sow at a medium rate when soil moisture is suitable to produce a reasonable stand but oversow if conditions are dry or drought-like for a similar result. Winter wheat mixes well with hairy vetch, winter peas, and red clover. Learn more about the growth stages of wheat by reading Wheat Growth Stages and Associated Management from the Ohio State University College of Food, Agricultural, and Environmental Sciences. 

Winter wheat should be terminated when flowering begins, around mid-May to early June. Mow or crimp to kill it, then cover it with a silage tarp to allow it to break down. Giving your soil three to four weeks to decompose debris is critical. Decomposing the wheat debris ties up nitrogen in the soil, which is crucial to the next crop. Add nitrogen fertilizer to boost your crops if necessary, primarily for leafy greens that require high nitrogen levels. Plant directly into the debris so the wheat can serve as a green manure or surface mulch. 

3. Hairy Vetch (Vicia villosa Roth)

Hairy vetch is part of the Leguminosae, or legume, family, so it builds nitrogen in the soil and provides much organic matter when it dies and breaks down. To sow, broadcast about four ounces per 100 square feet in a prepared garden bed. Water the seeds upon seeding and optionally add an inoculant to increase growth and nitrogen fixation.
Cover it with insect netting or a frost blanket while it germinates to keep hungry birds and chipmunks away. If you don’t have access to these items, step on the seeds to bury them or use a wire weeder to scratch them in and ensure they’re not fully exposed. 

Spring growth will be fast and furious if you sow hairy vetch in late summer. Give it ample time to produce long vines and dense foliage to help keep annual weeds down. 

Pro tip: You can mow down the long vines in the fall or spring to prevent the vetch from going to seed and allow new growth. This method will provide you with extra time to terminate and benefit the soil more in the meantime.
Our favorite no-till method is to mow the vetch in the spring, cover it with a silage tarp for several weeks, add a layer of compost, and plant our crops directly into the broken-down debris. The time between tarping and planting allows benefits like nitrogen-fixing to kick in, and the elimination of tilling keeps pesky weed seeds far beneath the soil surface where they belong.

4. Crimson Clover (Trifolium incarnatum) 

You may know that some cover crops are known for nitrogen fixing, but what does this mean, and how does it work? As a member of the legume family, crimson clover forms a deep root system with nodules at the ends. These nodules symbiotically partner with healthy soil bacteria, take nitrogen from the air and convert it to a usable form for other plants. It also scavenges for mineralized nitrogen, reducing groundwater leaching. 

Crimson clover’s incredibly robust taproot will improve soil drainage, reduce soil compaction, and reduce erosion. It performs well in all soil types, including sandy and heavy clay, and will attract beneficial insects like ladybugs and pirate bugs.  Growers have a few termination options: 

1. Mow it low, then till in the debris to add nutrients and biomass to the soil.
2. Mow and tarp the cover crop in a no-till system, leaving the debris to break down underneath. The debris will add nutrients, including high nitrogen levels, to the soil. Keeping the roots in will elevate the benefit of reducing compaction. 
3. Leave the debris in place after mowing to serve as an effective “chop-and-drop” living mulch. 

Like hairy vetch, the weeks between termination and planting the next crop will allow nitrogen-fixing benefits to kick in. Leafy greens benefit the most from growing after a leguminous cover crop, while a fruiting vegetable will not perform as well. 

Sow crimson clover in late summer or early fall to ensure enough height growth and establishment to sustain the approaching cooler temperatures. Crimson clover is hardy to USDA hardiness Zone 6, meaning it should survive the winter conditions. Otherwise, it will perish once the temperatures reach below 0°F (-18°C), and the debris will protect the soil surface. 

Related: How to Prevent Freezing Pipes: A Guide to Winterizing Your Garden's Drip Irrigation System

5. Field Peas (Pisum sativum)

Field peas are part of the larger species of “cowpeas” or “Southern peas” and are, in fact, not a pea at all but rather a type of bean. They’re a strong nitrogen fixer, can germinate in cold, wet soils, and have the added benefit of being harvested and fed to livestock or saved for seeds once they are dried. They’ll continue to produce vines and tendrils even after harvest. 

Field peas produce abundant biomass, add lots of organic mulch to your beds, and are long-season bloomers. They’re lovely to look at and don’t take much effort to maintain. They prefer neutral soil that’s well-draining and moderately fertile, although they’ll tolerate some misgivings. 

Broadcast the large seeds at any point in the season and rake them in to ensure good seed-to-soil coverage and protection from drying out or hungry critters and birds. Field peas do best up to USDA Zone 6 because they are fussy with extreme heat and humidity. Performance will suffer when temperatures are above 90°F (32.2°C) in the long term, including flower drop and reduced seed yields. Plant seeds from mid-August to September in USDA Zones 5 and below to ensure plants are about eight inches tall before the frost arrives. 

To get the full soil enrichment benefits, mow and incorporate under after plants have fully bloomed. Dead pea plant debris can be a mess in the spring, but it’s nothing a silage tarp and a swivel hoe can’t handle. 

Practical Tips for Small Gardeners

We’ve heard small-scale gardeners say cover cropping isn't worth it, but we promise it is. The crops that follow a well-managed and properly terminated cover crop feature lush foliage, increased yields, fewer diseases, and greater resilience to pest damage. 

How to Choose the Right Winter Cover Crop for Your Garden

The right cover crop for your setup fits in with your USDA growing zone, climate, and ability to sow, manage, and terminate it promptly. Ask yourself a few questions that may help:

• What is my intended outcome? 
• What is my sowing timeframe? 
• What is my management capacity? 
• How will I terminate?

Combining Cover Crops for Better Results 

While you can broadcast a single type of cover crop throughout garden beds and be successful, combining different varieties can elevate the benefits of each and give you more bang for your buck. Here are a few winning combinations and various situations that they work in: 

• Hairy vetch mixed with cereal rye: Perfect on sloped land that needs to combat topsoil erosion and loss of nutrients. The nitrogen-affixing properties of hairy vetch will supply much-needed nutrients to the following crop, whereas cereal rye roots will help hold the soil in place. 
• Oilseed radishes or mustards mixed with winter rye: Brassicas grow quickly, scavenge nitrogen from the soil, and reduce compaction and erosion. Their above-ground foliage will winter-kill, but their underground growth will help keep soil in place. Winter rye will suppress spring weeds and add loads of biomass to the soil when terminated. 
• Oats and field peas: Oats suppress weeds, add lots of organic matter, and provide something for peas to climb up. Peas will secure nitrogen for your next crop.  

Work with your local Extension Agency to determine an effective blend for your plot. There are so many fun combinations to experiment with. Take notes on sowing dates, germination rates, growth habits, winter performance, and spring activity. Record how and when termination occurs and what you plant there next. How did it perform? What were yields like? 

Terminating Cover Crops 

The size of your garden matters as it will affect how and when you terminate your cover crops. Many small-scale and container gardeners do not need to till and may not have a tilling implement, which can get tricky when terminating cover crops. Home gardeners can easily weed-whack, mow, or crimp cover crops, and using a silage tarp will help smother the debris. Use a broadfork or digging fork to turn over and mix in decomposed debris before freshening up your soil with amendments (if needed) and compost. 

Related: Using Silage Tarp for Organic Weed Control and Bed Prepping

Planting Techniques for Cover Crops in Small Gardens

Depending on the crop type and size of the seed, gardeners should plan to broadcast the seeds or add them to a shallow trench. Follow seeding guidelines and fully incorporate them so they aren’t exposed. Container growers should use less seeds than they think to avoid crowding.
Pro tip: Water the seeds, and then cover the container or garden bed with a silage tarp. Check on the germination daily and remove the tarp when you see sprouts. This method reduces damage from birds and critters, provides a dark, moist space, and increases germination rates. 

Should You Cover Crop Soil in Containers?

Container growing is an excellent way for small-space and apartment growers to continue their gardening journey, but it can be tricky to cover crop. If you use fabric grow bags and can bring them inside for the winter, follow recommendations on your desired soil outcomes. 

Tips to maintain soil health in containers, raised beds, pots, and grow bags: 

• Water consistently and evenly. We recommend using an irrigation kit based on your region’s weather, the container size, and what’s growing. Automate if necessary to ensure proper watering. 
• Begin with high-quality, organic potting or seed-starting soil. 
• Ensure soil is well-draining and loamy. Add vermiculite to add “fluff” and assist with drainage. 
• Soil test each season to determine amendments required. 
• Use worm castings when transplanting. 
• Inspect for diseases each season. Empty soil and clean containers if needed. 
• Add aged manure or compost each season. Mix well.
  

Don’t be afraid of cover cropping in pots and containers, even small ones. As crops conclude their season, clear out debris, sow a cover crop, and treat it like any other direct-sown crop. Water it well, place it in sunlight, and protect it from critters. 

Buckwheat is an easy-to-terminate summer cover crop that pollinators love. In colder regions, growers should consider winter rye combined with peas and oats. Freshen up tired soil with Sudan grass or sorghum. It is an excellent winter-kill mulch option and will add much-needed organic matter to the soil.
Related: How to Test Soil pH Before Planting — and Why You Should

FAQs

What is the best winter cover crop for a small garden?

Oats, ryegrass, buckwheat, and clovers are considered workhorses in the farming world. You can adjust each of these crops to work in a small-scale garden. 

How do winter cover crops improve soil health?

Depending on the crop type and variety, winter cover crops reduce soil erosion, build organic matter, cover soil surfaces with biomass, and fix nitrogen, making it available for the next round of crops. Crops with deep taproots can help with soil compaction and aeration, improving soil tilth and allowing nutrients and water to absorb and drain properly. 

Can winter cover crops be grown in raised beds?

Yes, you can use cover crops in raised beds; and you should! Have an effective termination plan for the spring that allows you to manage the debris, take advantage of the cover crop’s benefits, and still get your bed flipped in time for spring and summer plantings.

What are the planting times for winter cover crops?

Planting times depend on your region, growing zone, garden plans, and type of cover crop. You can plant hairy vetch in mid to late summer, so it has time to grow tall and dense. Winter rye can germinate when temperatures have dropped near freezing, and although you won’t get a tall winter rye crop, the roots will reduce run-off and avoid erosion. 

How do I manage cover crops in a container garden?

Solarizing, mowing, tarping, and cutting are standard methods of cutting down cover crops in container gardens. You can also let the frost kill winter-kill options. The crop's biomass will cover the soil surface, and the roots will help reduce erosion and drainage. 

Written by Jenna Rich of Partners’ Gardens LLC.