Cover Crops

Kenosha News – August 4, 2016

Barb Larson, Horticulture Educator

Question: My vegetable garden is quite a few years old. There were several problems in the garden early on so I harvested as much as I could. Instead of planting again, I’d like to try a cover crop. I’ve heard cover crops are a good idea even in a backyard garden. Is green manure the same as a cover crop? Do you have any suggestions? V.S.

Answer: Planting a cover crop is a great idea. It will improve soil structure and fertility, reduce erosion, decrease weeds, and provide habitat for beneficial insects. Cover crops are tilled into the soil adding organic matter, increasing nutrients, improving drainage in clayey soil or adding water-holding capacity in sandy soil.

Green manure is a type of cover crop using plants in the pea/bean, mustard or grass families. Green manure is grown for the organic matter and nutrient benefits.  Members of the pea/bean family are especially beneficial because they increase soil nitrogen when tilled into the garden.

Cool season cover crops should be planted in the next six weeks for fall growth.  Since your vegetables are harvested, a fall cover crop would be ideal this year. You have a number of options. Oats are a good choice for home vegetable gardens. Oats die over winter making garden preparation faster and easier next spring. Most cool season cover crops are dormant over winter and grow again in spring. These plants need to be mowed and worked into the soil before planting vegetables. Examples are field peas, forage radish, oilseed radish, winter rye, annual ryegrass, and winter wheat.

Warm season cover crops are planted in spring or summer. They may be part of a multi-year crop rotation system or replace the vegetables for part or all of one growing season. Warm season cover crops outgrow weeds, prevent erosion, and reduce soil hardening and cracking. Choices are buckwheat, sweet clover, and field peas.

Regardless of planting time, remove debris and rake the soil surface smooth before planting your cover crop. Broadcast the seed across the planting area and rake in lightly. Water after sowing. Cut the plants down with a mower or trimmer as they begin to flower. Work the plant tops into the soil with a shovel, pitchfork or rototiller. Most of the leaves, stems and roots from the cover crop will decompose in two to three weeks. After which, vegetable planting may begin. UW-Extension factsheet on cover crops may be found at Put “cover crop” in the search box.

Barb Larson is horticulture educator for Kenosha County UW-Extension. Questions can be emailed to or call 262-857-1942.