Cover crops for a green winter vegetable garden

Winter rye/Austrian winter pea

Fall planted cover crops make me feel good for two reasons. First I know that after they grow over the winter and I turn them under in the spring, I will have improved my vegetable garden soil. Second is the novelty of looking out my window in the depths of winter and seeing green plants in my vegetable garden.

Plant cover crops in fall from mid-September to mid-October on the Front Range of Colorado. With this year's warm fall weather you probably could have planted through the end of October. The season before we had subzero weather the second week in November so late plantings likely would not have survived. Plants require at least a month of moderate fall temperatures to establish before winter cold slows growth and soil temperatures drop below 40 degrees F.

Winter rye/Austrian winter pea or winter rye/hairy vetch mixtures work well for the Front Range. Many gardeners plant winter (cereal) rye. Grass (the winter rye) alone works well for increasing soil organic matter but if you want the advantage of the nitrogen adding abilities of legumes, add winter pea or hairy vetch in a mixture. Hairy vetch is hardier than winter pea and winter rye is very hardy. Plant at 4 to 6 ounces per 100 square feet except a lower rate of 2 to 3 ounces for vetch.

Water at planting and perhaps once or twice more to establish. In general winter snows will provide enough moisture for plants although you could always winter water in extended warm, dry winter weather if you feel you need to.

In spring spade or till the crop under the soil burying both tops and roots. Keep in mind that after turning under your cover crop you should wait a month for plants to break down before planting vegetable seed or transplants. If you need the garden space to start spring crops and don't have a month to wait, harvest cover crop plants and coarsely chop to decompose in the compost before adding them back to the garden soil between your spring and summer crops.

Cover crops should be a routine part of maintaining a healthy and productive garden soil. Online sources for cover crop seed include Johnny's Selected Seeds and Urban Farmer Seeds.

Photo credit: All photos credit Carl Wilson.