
It’s the time of year when the gardening season is coming to an end, and the days are getting shorter, so it is very tempting to let your garden beds rest until spring. But this dormant period is the best time to invest in the health of your soil. Planting cover crops—often referred to as “green manures”—will rejuvenate your soil, prevent erosion, and suppress weeds, preparing your garden for a strong and healthy return next year.
Cover cropping refers to planting of particular crops at off-season with the intention of making the soil fertile and healthy for crops by depositing nutrients on the soil. This type of crop is then turned into the soil before other crops are planted; they therefore serve as organic fertilizers. Six Green Manures to Sow in Autumn and Revive Soil over Winter.
1. Winter Rye (Secale cereale)
Winter rye is perhaps the most popular cover crop in terms of fall sowing, and rightly so: it’s hardy, easy to grow, and has a number of benefits. Some of them are:
Soil Erosion Prevention: The thick root system keeps soil intact during winter rains and snowmelt periods.
Capture Leftover Nutrients: Winter rye fixes leftover nutrients on the soil, which otherwise leach into the subsoil.
Weed Suppression: Its growth rate checks weed growth effectively.
Planting Instructions: Sow winter rye at the end of summer, to early fall. Let’s say around 6-8 weeks before the first frost. Scatter seeds evenly, and lightly rake them into the soil. It tolerates poor soil conditions, but thrives between USDA zones 3-7.
2. Crimson Clover (Trifolium incarnatum)
Crimson clover is a beautiful and effective cover crop that also fixes nitrogen in the soil, making it a great choice for gardens with nutrient deficiencies. It also attracts pollinators early in spring by its bright red flowers.
Nitrogen Fixation: Like other legumes, crimson clover forms a symbiotic relationship with soil bacteria to convert atmospheric nitrogen into a form plants can use.
Erosion Control: Its dense foliage protects the soil surface.
Aesthetic Appeal: Crimson clover is a beauty to behold, splashing color into your garden.
Planting Tips: Sow seeds in late summer or early fall, lightly covering with soil. It prefers well-drained soils and does well in zones 6-9.
3. Hairy Vetch (Vicia villosa)
Hairy vetch is quite versatile, tolerating a wide range of climates and soil types. It is particularly valued for its ability to fix nitrogen and enhance soil fertility.
Nitrogen Fixation: Hairy vetch can contribute substantial amounts of nitrogen to the soil.
Cold Hardiness: It is more cold hardy than many other cover crops.
Soil Aeration: Its deep roots break up compacted soil, improving drainage and aeration.
Planting Tips: Sow hairy vetch seeds in late summer to early fall. It’s ideal for zones 3-10 and pairs well with winter rye for a dual-purpose cover crop.
4. Field Peas (Pisum sativum subsp. arvense)
Field peas are one other legume that, being a great cover crop, help add nitrogen and provide excellent ground cover against the erosive tendency of the water.
Fast germination: This makes them able to suppress weeds after a very short time.
Efficient nitrogen fixation: They enrich the soil for further plant utilization.
Cold Tolerance: Is not as intense as in many other cover crops, but these can thrive fairly well under gentle winters.
Planting Tips: Field pea seeds should be planted in early fall when they should be put approximately 1-2 inches into the soil. These crops grow really well in zones 6-9 and soils that are fertile and well drained.
5. Buckwheat (Fagopyrum esculentum)
While most commonly used as a summer cover crop, buckwheat can also be seeded in the early fall as long as winter is mild enough. It makes an excellent selection for those hoping to increase soil life quickly.
Phosphorus Mobilization: Buckwheat brings phosphorus available in the soil into a soluble form, making it more readily useable by the plants.
Suppresses Weeds: Its rapid germination and development suppress weeds.
Bee Attraction: Buckwheat flowers attract pollinators, which gives it an ecological value.
Planting Tips: Sow buckwheat seeds in late summer or early fall. There should be at least 30-40 days of growth before frost. It’s best suited for zones 3-8.
6. Mustard (Brassica spp.)
Mustard is a dynamic cover crop with special benefits such as pest and disease suppression.
Biofumigation: When put into the soil, mustard releases chemicals that manage soil-borne pests and diseases.
Fast Germination: It germinates very fast, thus offering rapid ground cover.
Organic Matter: Mustard offers ample organic matter to the soil when it is added.
Planting Tips: Sow mustard seeds in early fall, 6-8 weeks before the first frost. It thrives in zones 4-9 and prefers well-drained fertile soil.
Benefits of Cover Cropping
Here are several reasons to plant green manures in the fall for your garden:
Soil Fertility: Legumes like clover, vetch, and peas make the soil rich in nitrogen, so synthetic fertilizers can be less required.
Prevention of Erosion: Cover crops prevent soil erosion due to wind and water.
Competition to Weeds: Cover crops grow faster, and hence suppress weeds. No use of herbicides.
Soil Erosion Improvement: Crop roots of plants such as rye and vetch move deep into soil improving aeration and drainage.
Insect and disease control: Use of biofumigant crops like mustard and other crops help inhibit pathogens in the soil.
Increase biodiversity: They attract beneficial insects and increase soil microbial activity
How to Control Cover Crops During Spring
Cover crop management is required for proper realization of benefits:
Timing: Cover crops should be terminated 2-4 weeks before planting your main crops. This allows the organic matter to break down and release their nutrients into the soil.
Methods: You can mow, chop, or till cover crops into the soil. For no-till gardening, cut them at the base and let them decompose into the soil as mulch.
Incorporation: If you till the soil, the soil will have had enough time to be mixed with the soil for the pests not to hide in the residues.
Conclusion
Cover cropping is one of the simplest and most powerful ways to recharge your soil over winter. Planting green manures such as winter rye, crimson clover, hairy vetch, field peas, buckwheat, and mustard can enhance soil fertility, prevent erosion, and prepare your garden for a bountiful growing season. A little planning this fall will set the stage for healthier plants and higher yields in the spring.