What is a cover crop and how do you use them in your garden? Cover crops are essentially sacrificial crops that are planted, allowed to grow, then mowed over and tilled under to allow the organic matter to decompose.
Don’t Call it Come Back
Cover crops have been used for centuries but not until recent studies by the Rodale Institute and other gardening research centers have they been thrust back into the spotlight. Planting a cover crop under a crop of corn or other vegetables is often used in larger scale production and is a little more difficult in most backyard gardens. Most home gardeners will use a winter type of cover crop which is what we will discuss here.
Improving the Soil
The best cover crops vary greatly by region depending on things like winter hardiness and speed of germination. Winter is a great time to work on improving the soil but let’s face it, most of us don’t want to work in the garden when the weather hovers around the freezing mark for weeks on end. Not to worry, winter cover crops are actually planted in the fall and protect the soil over the winter months. All it takes is a little know-how and some planning to help improve your soil for the next growing season. By planting a cover crop in late summer or early fall and letting it over-winter you can improve your soils organic matter and fertility.
There are basically two types of winter cover crops: crops that are killed by cold but have enough biomass to protect the soil and those that remain alive through winter and resume growth in spring. Sown in summer, they will put on a lot of growth before being killed by heavy frost. The killed mulch and root mass will hold the soil in place until the following spring. plants that may be grown for winter killed mulch include,
- field peas
The disadvantage to this type of cover crop is that you have to clear the land and plant the cover crop early enough to get significant amounts of biomass to hold the soil over the winter. That could mean planting in our area as soon as Late July or early August, or it could require undersowing the cover crop in a summer crop such as tomatoes, peppers or sweet corn. The big advantage of a winterkilled cover crop is that the mulch is easy to till under in spring and the land can be planted right away.
Cover crops that live through winter or that go dormant and renew growth in late winter, can usually be planted after summer vegetable crops. They will grow in fall and establish root systems that protect the soil over winter. Some examples of crops that will survive winter (depending on winter low temperatures) include
- winter rye
- winter wheat
- hairy vetch
- Austrian winter peas
- crimson clover
Winter Rye and hairy vetch are recommended for our region with Winter Rye being the most common one we sell.
In regions where these crops survive winter, they will grow vigorously in early spring. In early spring they will need to be mowed close to the ground to stop growth and then tilled into the soil. The breakdown of the cover crop debris can tie up nitrogen, it’s a good idea to wait two or three weeks before planting.
Even in a small raised garden bed, the benefits of growing a cover crop are immense. I encourage you to try a cover crop at the end of the season; I promise the rewards will be well worth the effort.