What if your garden could work for you while you cozy up by the winter fire? Fall cover crops are the secret to fertile spring soil with minimal effort. If you seed certain grass or legume species in the autumn, the plants and soil microorganisms can work together to nourish your soil all winter.
Cover cropping is the science and art of building and protecting soil when it’s not used to grow vegetable or fruit crops. It is a key tenet of no-till and regenerative growing practices because it ensures your most valuable garden resource — the soil — is covered during the harsh winter months. Without cover crops, your garden beds are vulnerable to erosion from wind and rain and intrusion from weeds.
If you want next spring to be your best gardening season yet, sow one or more of these 9 fall cover crops!
What is the Best Cover Crop to Plant in the Fall?
Plant fall cover crops a month or longer before the first frost to enrich soil and prevent erosion.
Great fall cover crops include oats, annual ryegrass, winter wheat, hairy vetch, clover, and Austrian winter peas. You may also consider cowpeas, barley, or buckwheat in warmer temperate regions (zones 8 and above). These species nurture your garden over the winter and protect the soil from erosion or compaction. They add organic matter and fertility while creating a nice mulch or compost input the following spring.
The best time to seed fall cover crops in the garden is about one month before your expected first frost date. In cold northern regions (zones 7 and below), fall cover crops usually must be seeded by October to ensure a strong stand. Extra frigid regions should establish their cover crops early, while warm southern regions can wait until November and intermix warm-weather cover crops like buckwheat for fast-growing biomass.
Benefits of Fall Cover Crops
Fall-seeded cover crops act as a protective winter shield for your garden, preventing winter weed growth.
Think of fall-seeded cover crops as your garden’s nourishing winter blanket. They insulate the soil from harsh weather while improving the soil fertility for next year’s crops.
Cover cropping is essential for organic, no-till, and regenerative growers because it keeps the underground ecosystem of soil microorganisms protected and thriving throughout the winter. Moreover, it covers bare soil so perennial winter weeds don’t get out of hand while you’re staying warm indoors.
The benefits of fall cover crops include:
Leguminous cover crops add nitrogen to the soil, and the organic matter from grassy cover crops improves soil fertility. This means less fertilizer or compost additions are needed to supply your plants with their nutrient needs. Some species, like buckwheat, also draw other essential nutrients like phosphorus to the upper strata of the soil where young plant roots can readily access it.
Bare soil is like a giant welcome sign for weeds. Seeding cover crops in the fall ensures that your garden beds are shielded from weed invasion all winter. The growth of these plants chokes out weeds and creates a dense weed-smothering mulch after they’re chopped down.
Wind, rain, and snow are major causes of erosion, which causes your topsoil to disappear, blow away, or wash away. Cover crops are scientifically proven to significantly reduce erosion. The roots anchor soil particles in place so you don’t lose any investments you’ve made in your garden beds.
Cover crop roots help penetrate lower soil layers and break up compaction, making fluffier, aerated soil for your spring vegetables.
Winterkill vs. Frost-Tolerant Cover Crops
When choosing cover crops, research whether they die off in frost or endure the winter.
When selecting cover crops, consider whether the species will die back in the frost or survive the entire winter. If it is frost-tolerant, you must find a way to kill it in the spring. Some cover crops are chosen specifically because they winterkill and leave a nice fluffy soil-covering residue behind. Winterkill species like oats, clover, and barley are often favored by cold-weather gardeners because they don’t require as much work in the spring.
Conversely, frost-tolerant crops can provide much more biomass and organic matter because they keep growing all winter. Their root systems are more robust, and the foliage accumulation provides extensive mulch.
The key to successful cover cropping with frost-tolerant species is terminating them at least 2-3 weeks before you plant your spring crops. As we’ll cover below, you can use a mower, loppers, pruners, or a tarp to smother the plants in place. No herbicides are needed!
- Choose Winterkill Cover Crops: If you live in a colder climate and want a more manageable garden in the spring, choose frost-tender species that winterkill and can easily be raked aside for spring planting.
- Plant Frost-Tolerant Cover Crops: If you live in a milder climate and want maximum organic matter and nutrient contributions with continuous soil cover, choose a cover crop that can withstand your lowest winter temperatures.
9 Best Fall Cover Crop Species for Gardeners
Green manure crops like beans and rye grass have been used since the ancient Greek, Roman, and Chinese empires to improve soil and prevent erosion over the winter. Modern farmers use a diverse range of cover crops to nurture fallow fields commercially, but gardeners need to make a few modifications for small-scale growing.
You probably don’t have a tractor to chop down the crop, let alone harvest the hay when it’s done. Cover crop termination (killing the cover in the spring) is essential to plan for because you don’t want your fall clover to become a nuisance next season. You also don’t want ryegrass popping up all over the garden.
These cover crop species and termination tactics are designed for small-scale gardeners who want to reap all the benefits of cover cropping without extensive machinery.
Oats (Avena sativa)
This cover crop has rapid germination and dense growth.
- Best for: Boosting Organic Matter and Suppressing Weeds
Oats are a classic fall-seeded cover crop with many benefits for the home gardener. The seeds germinate quickly and provide rapid ground cover. A dense stand easily suppresses weeds and prevents erosion through even the harshest winters. The fibrous roots reach about 6-8” in the soil, making this species excellent for adding organic matter to the upper layers.
Oats are cold-tolerant but do best when sown 4-6 weeks before your first frost date. They need some time to establish before super frost temperatures arrive. Ideally, your oat stand should be at least 6” tall before frost. The plants can grow up to 4 feet tall in mild winters, offering an abundant source of carbon-rich organic matter.
Seed your oat cover crop about 1-2” deep. Broadcasting or scattering by hand is usually the easiest, then sprinkle the top with a thin layer of soil or press into the ground. If there isn’t any rain, provide plenty of moisture in the first 1-2 weeks. Oats require up to 2 weeks to germinate, but pre-soaking the seeds speeds up the process.
How to Terminate It
Oats winterkill at about 20°F in zones 7 and colder, which means heavy frosts will naturally kill the crop, and the leaves will rot in place. When you are ready to plant, chop any remaining upright stalks and push the oat residues to the side, or gather the remnants of the plants and use them in your compost pile. If the roots are in the way of your planting, hoe them or add a 1-2” thick layer of compost on top.
In warmer zones, you must chop down your oats in the spring before they set seed. The milk or “soft dough” stage is most desirable because the plants have started forming seed heads (great for adding nutrients to the soil), but the seeds aren’t yet mature enough to germinate. It’s very important to catch oats before the seeds mature. Otherwise, they will scatter oat seeds all over the garden! You don’t want your cover crop to become a weed!
For in-ground beds, it’s easy to mow oat grass very low with a lawn mower. In a raised bed, you can use loppers or pruners to chop the foliage back close to the ground, then use a scuffle hoe to loosen and incorporate the roots. Use the chopped dead foliage like straw mulch on the bed or take it to your compost bin as a carbon input.
Winter Rye (Secale cereale)
Rye protects soil from erosion, grows deep roots to break up compacted soil, and accumulates biomass.
- Best for: Cold Climates and Late Planting
Winter rye is your best bet if you’re late to the game on fall cover crops! This extra cold hardy plant can germinate and grow in temperatures as cold as 34F. Even zones 4 and 5 can plant winter rye as late as November and still get a pretty good stand.
Winter rye is the cover crop of choice for northern farmers and gardeners because it is highly effective at protecting the soil from erosion and compaction underneath snow. Its tolerance for extra cold weather means this cover crop can stay standing until spring. It accumulates lots of biomass while suppressing weeds and anchoring its roots up to 16” deep in one winter! This is an awesome choice if your soil is compacted or has a hardpan layer.
Sow winter rye as late as November in warmer zones, but aim for late summer to early October in zones 3-7. Broadcast the seeds and press or rake into the soil. The denser you sow, the more biomass and weed suppression you will get. Seed extra heavily in areas with compacted soil.
The seeds are a bit finicky about depth, so be sure they are no deeper than 2” into the soil. Seeds that are sown deeper than 2” will not come up.
The rye will take 1-2 weeks to germinate. If there isn’t rain, be sure to provide additional moisture. The plant grows slowly throughout the winter but usually reaches 3-6 feet tall by spring. Beware that deer love to browse on this plant when winter food is scarce. Fortunately, rye handles grazing well and should regenerate without issue.
How to Terminate It
Like oats, you want to catch winter rye before the seeds mature. Immature seed heads are OK and can be a nice source of nitrogen. Use a lawn mower, loppers, or pruners to cut back rye to the ground 1-2 weeks before spring planting. To use it as mulch, chop it down and leave it in place, or consider moving the mulch to a perennial bed. Otherwise, compost the residues and leave the roots in the soil to nurture the microbes.
Winter rye is a great fodder for livestock, so don’t hesitate to feed it to your chickens! Better yet, if you can fence your chickens over a garden bed, they can chop down the crop for you!
Winter Wheat (Triticum aestivum)
Winter wheat is an excellent choice for temperate zones, offering erosion protection with deep roots and weed suppression.
- Best for: Harsh Winters and Boosting Organic Matter
This cool-season grain is perfect for fall planting if you live in a temperate zone. Winter wheat provides robust erosion protection by anchoring its roots up to 3.5 feet into the soil! The dense above-ground growth suppresses all weeds, reducing future competition for nutrients and water.
But the thing I love most about winter wheat is its contribution to organic matter. This climate-friendly choice has also been heralded for its sustainability because it is proven to sequester carbon in the soil. In other words, winter wheat is particularly adept at sucking carbon out of the atmosphere and locking it away inside soil organic matter.
When the grassy leaves decompose in the spring, they become a valuable mulch or compost input. Most straw you purchase from garden stores is made of hollow wheat or rye plant stems.
Whether you live in a mild zone or an area with harsh winters, wheat will provide green growing coverage throughout the dormant season. If the crowns are properly hardened and preserved at least 1” deep beneath the soil surface, the plants can handle a whopping -11°F or colder. The key to a strong stand is seeding early. Mid-September through early November is ideal in most climates. If your winters are extra cold or you accidentally seed later, you will need to sow more seed to ensure a denser stand, and the wheat won’t produce as much biomass.
Sow winter wheat ½ to 1.5” deep in the soil. You can broadcast the seed by simply scattering it in your garden bed. Use a bucket to shake a thin layer of compost or soil over the top. Keep the soil consistently moist for the first week. The seeds should germinate in 3 to 5 days or longer if you sow them deeper.
How to Terminate It
Terminating winter wheat is very similar to oats or rye. You can mow it down before it sets seed. If you don’t have a mower, prune the plants off at the base. Let the residue break down for 2-3 weeks before planting spring crops. Use the dried straw to mulch in place, or add it to your compost.
Crimson Clover (Trifolium spp.)
For rapid soil improvement, choose crimson or red clover as a cover crop, as it fixes nitrogen.
- Best for: Adding Nitrogen
If you want to rapidly improve your soil fertility, crimson clover or red clover is your new best cover crop friend! This nitrogen-fixing legume rapidly covers the ground and controls weeds very well. The roots scavenge work with symbiotic bacteria to fix nitrogen from the atmosphere, creating more plant-available nitrogen for future crops.
Clover is best seeded in between August and November. Plant seeds shallowly at ¼ to ½ inch deep. Lightly rake or press in, and don’t cover. Keep the soil moist and wait 7-10 days for germination. This species is often used in cover crop blends with grasses, as described below.
My favorite thing about clover is its ability to loosen tough soil while adding nitrogen. The plant grows very quickly and reaches up to 3 feet tall. If it survives the winter and you leave it in place in spring, it will produce nectar-rich flowers around April. These flowers are very beneficial for pollinators and predatory insects.
How to Terminate It
Clover is winterkilled in zones 5 and colder, making it easy to manage in spring. Generally, negative temperatures knock this legume to the ground. If it doesn’t winter kill in a warmer zone, you need to take extra care to till it or use a tarp to smother the plant so it doesn’t become a nuisance in your vegetable bed. Clover can be very aggressive, so you don’t want it competing with your vegetable crops.
Tarping is my termination strategy for clover because it thoroughly suppresses the plant before you seed your vegetable crops. If possible, mow the clover down very low, then put a tarp over the bed for 1-3 weeks. The lack of sunlight will naturally deplete and kill the cover crop, leaving the residues to rot in place.
When you pull up the tarp, add a 1-2” layer of compost and broad fork if desired, then plant your bed as usual! Heavy-feeding crops like brassicas and tomatoes will grow vigorously in the clover-nourished residues!
Hairy Vetch (Vicia villosa)
Hairy vetch is an excellent green manure that fixes nitrogen, thrives in cold weather, and can cover large areas.
- Best for: Adding Nitrogen and Suppressing Weeds
This underappreciated plant is one of the best nutrient-boosting green manures that dramatically reduces weed pressure. The leguminous nature means it has the same symbiotic bacteria as clover. It scavenges nitrogen and makes the soil more fertile for your next crop.
Hairy vetch is cold, hardy, and great for fall sowing. It needs moist soil but otherwise fares for itself throughout the winter. The vigorous vining habit chokes out all other plants, so it’s great for beds with perennial weeds. This vetch grows up to 3 feet tall and 12 feet wide. However, it does self-seed, and you must terminate it early to ensure it doesn’t become a garden nuisance.
Seed hairy vetch 1 to 1.5” deep at a dense rate using your hands or a manual broadcast seeder. A bucket of topsoil or compost makes it easy to sprinkle soil over the seeds and ensure they are covered. They need good seed-to-soil contact, so some hand tamping can press them into place.
Keep the bed moist until germination, which takes 10-14 days. If you seed later in the season, the germination could be slower due to cold soil. Plant at least 30 days before the expected first frost date for the best stand.
How to Terminate It
Hairy vetch can become a problematic weed if you don’t kill it. In the spring, use a mower to chop the residues super low or rototill the cover crop in place. Use the same tarping method described in the clover section for a no-till alternative. A tarp is the easiest way to thoroughly smother the plant while retaining all the soil nutrients for your next crop.
Austrian Winter Peas (Pisum sativum)
Austrian winter peas, one of the most cold-tolerant leguminous cover crops, improve the soil and are hardy despite the cold.
- Best for: Adding Nitrogen in Cold Climates
Another popular leguminous cover crop, Austrian winter peas, are well-suited for cold regions. Incorporating this species in your fall crop rotation can improve soil nutrient availability and reduce reliance on fertilizers. These peas are unique because they can withstand 18°F without snow cover and down to negative temperatures when insulated by snow! They are usually rated as hardy in zone 6 or warmer and provide a nice winterkill cover in colder zones.
Seed Austrian peas 1-2 inches deep and cover them with up to 2 inches of soil. You can plant them as late as November, but earlier is better for a tall stand. Plants should be about 8” apart, but it’s OK to guesstimate. Water them well and ensure the soil is mildly cool. Hot late summer weather can hinder this cover crop’s establishment.
How to Terminate It
Cut down the peas in spring after plants have reached their growth peak but before they start setting pods. If you notice flowers, it’s time to chop!
Mow, prune, cut, or lop the plants at the base and leave the residues to decompose for 1-3 weeks before planting your veggies. Alternatively, move the foliage to your compost pile and leave the roots intact. Cover with a 1” layer of compost and seed your next crop.
Sorghum / Sudangrass (Sorghum x drummondii)
Terminate sorghum cover crops in early spring for use as mulch. Avoid late planting or heavy frosts.
- Best for: Mild Winters, Boosting Organic Matter, and Suppressing Nematodes
Anyone who has faced root-knot nematodes should know about this unique grass! Sorghum, also called sudangrass, is scientifically proven to suppress plant-harming nematodes and improve the yields of subsequent crops. This tropical grass is also fast-growing and excellent for adding organic matter in zones with mild winters.
Sorghum prefers a mild 60°F to germinate, meaning it needs to be sown in late summer in cooler regions or can be grown throughout winter in subtropical zones 9 and warmer. The plant kills at the first frost, so you must establish a nice stand if you prefer for the grass to create a dense mulch.
Seed sorghum ¾ to 1” deep and lightly cover seeds with soil. Consistent moisture and warmth are needed for germination, which can take 14 to 21 days. The strong root systems establish quickly, and the grass can grow 5 to 7 feet tall if you leave it in place long enough. Most gardeners terminate this heat-loving grass in early spring and use it as mulch. Avoid planting this crop if it’s late in the season or your zone gets super heavy frosts.
How to Terminate It
Scythe, chop, or prune sudangrass in the spring, just like the above plants. Try to terminate 1-2 weeks before planting. The grass is usually too tall to use a tarp. Use the dry straw as a deep mulch. Avoid letting it go to seed.
Barley (Hordeum vulgare)
Efficiently shading and suppressing weeds, barley is great for unirrigated, weedy, or grassy areas.
- Best for: Boosting Organic Matter in Zones 8 and Warmer
Barley is an excellent overwintering cover crop for zones 8 and warmer. It provides a lot of organic matter and reaches its fibrous roots up to 6.5 feet in the soil. The root hairs penetrate and open new aeration channels, improving overall soil structure and water infiltration.
The plant is a nutrient scavenger, meaning it accumulates nitrogen and other minerals. These become available to your crops whenever you incorporate barley residues back into the earth, where microorganisms can break them down.
Barley is quick to establish, out-competing and shading the weeds. It produces allelopathic chemicals to suppress weed growth, making it excellent for those weedy or grassy garden beds you constantly have to tend. I love barley for garden areas without irrigation because it tolerates poor soil and doesn’t mind a bit of winter drought once established. However, barley does not do well in waterlogged zones.
Seed at a depth of ¾ to 2” and scatter soil over the top of the bed. Plant before November for the best results. It cannot survive harsh winters and is best reserved for mild climates. The plant overwinters excellently in many western and southern regions. If you plant it in zone 7 or colder, seed in late summer to ensure a strong stand before frosts arrive.
How to Terminate It
Barley is prized as an easy-to-kill companion crop and soil protector. You can quickly mow it down or chop it with pruners without worrying about it returning as a weed. Leave the residues to decompose in place for maximum organic matter additions.
Some people like to till barley in to make nutrients more quickly available. As always, be sure that you terminate it before seed heads form!
Fall Cover Crop Blends
Opt for diverse cover crop blends to reap multiple benefits through pre-mixed blends or by creating your own mix.
- Best for: Improving Soil Structure and Fertility
Why plant one cover crop when you could plant several? You can find a plethora of pre-mixed cover crop seed blends to reap the benefits of several species at once. You can also shake your own mix together in a bag before seeding.
For example, popular blends include:
- Soil Compaction Remedy: A blend of barley, daikon radish, and turnips is perfect for breaking up heavy soil.
- Erosion Protection: The popular blend of oats and rye is chosen for their erosion-protection properties and deep root systems. These are great for hillsides or areas with lots of winter rain.
- Nutrient Enhancement: Blend several legumes together, such as clover, vetch, and peas, for maximum nitrogen fixation.
- Pest and Disease Suppression: Mustards, forage radishes, and sudangrass are great for mixing into areas that have problems with diseases or nematodes. These plants produce glucosinolates and other compounds that naturally suppress harmful organisms.
Remember, diversity is resilience! The diversity of root depths and leaf shapes can offer more habitat and food for soil microorganisms. Don’t be afraid to experiment with different blends to see what plants work best for your garden.
Final Thoughts
Cover cropping is a tremendous positive step toward a more sustainable and productive garden. These plants protect the soil over winter and make your spring even easier. When choosing a cover crop, remember to consider the winterkill temperature and your particular goals for soil improvement:
- If compaction is an issue, choose deep-rooted crops.
- If fertility is low, go for legumes.
- If nematodes are an issue, try sudangrass.
- If you need many benefits, choose a blend.
- If you don’t want to chop it down, make sure it winterkills in your zone.
- If you want it to grow all winter, ensure it’s frost-hardy.
