by Linda Carloni, ABG Board member and Master Gardener
Cover cropping may sound like an advanced practice, but it can be pretty simple and it’s really good for your soil and for the environment. Cover cropping for food gardeners is planting a non-food crop, generally legumes and cereals, and allowing it to grow for several months in order to improve the soil when your garden beds aren’t occupied with growing a food crop. Most often for home gardeners, cover crops are grown in the fall and winter.
Cover crop benefits
- Legume cover crops add nitrogen to the soil, helping restore what your warm season vegetables used up, without the environmental cost of synthetic inorganic fertilizers, which frequently are produced from petrochemicals. Legumes (beans, peas, vetches and clover) have the ability to pull nitrogen from the air into root nodules in the soil. When the plants die and their residues are returned to the soil, that nitrogen becomes available to the next plant occupying the soil.
- Cover crops increase soil organic matter, the same thing you achieve with compost.
- Cover crops keep living roots in the soil, improve water permeability, create and maintain soil pore spaces, build nutrient-holding capacity, and improve soil structure.
- Cover crops help with weed control, a big problem in empty vegetable beds in the rainy season, as well as with erosion and dust control.
- Cover crops also maintain the soil food web where they are planted, keeping it active to assist your food crops next season.
- Cover crops sequester carbon from the air into the soil. Like all plants, cover crops naturally absorb carbon dioxide from the atmosphere during growth and their roots exude carbon as carbohydrates that nourish soil microorganisms. When the microorganisms and plants die they break down and build up the carbon stored in the soil.
How to do it
Cover crops should be planted soon, so they get as much sun as possible as we head into winter. For the beginner, a cover crop seed mix is easiest – it should contain both legumes and cereals (like oats, barley or rye). Clear the bed and broadcast the seed in the quantity recommended by the package. Use a rake or garden fork to work the seed in and cover it with a little soil. Water the seeds in when planted, and keep them moist until they sprout. If it’s a very dry winter, you may need to continue to water if the plants wilt.
In the spring, use garden shears to cut the cover crop down. It is best to cut the legumes down before they start using their stored nitrogen to make seeds – just after they bloom. Just leave the roots in place, they add organic matter and improve drainage. You can then dig the crop in, leave it on the surface to compost in place and serve as a mulch, or compost it in your compost bin. If you dig it directly into the soil, wait at least a couple of weeks to a month for the crop residue to break down before planting.
Your spring plantings will thank you!