Cover crops and your lawn

It was at the end of the growing season. I had just created terraces behind my home. It was too late for a fall garden. I asked Ray Ridlen, the County Extension Educator and Master Gardener advisor at the time, if I should mulch the terraces before winter. His answer was, “Yes, that would be good.” Then he said, “How about a cover crop?” I asked, “What is a cover crop?”

What is a cover crop? Generally a cover crop is grown when the garden soil is idle, but can be grown between rows of vegetables or fruit to serve as living mulch. They are grown during fallow periods to increase organic matter, aerate compacted soil, protect soil from erosion, and/or smother unwanted weeds. They are sometimes called green manure crops.

Now is the time to consider planting a cool-season cover crop. Cool-season cover crops will survive through the winter. They are planted from mid-September until the end of October, and left over the winter to provide protection from soil erosion. They need to be planted early enough so their roots develop before winter but late enough so they do not complete their growing cycle before the weather gets cold.

Why plant a cover crop? Their deep roots absorb nutrients from the soil that could otherwise leach away. When tilled under, cover crops decompose and release those caught nutrients. This is one of many reasons to plant a cover crop. Their deep roots prevent soil compaction. They prevent erosion. They improve drainage and aeration. They can help suppress harmful soil nematodes. Nematodes are parasites which tend to be specific in which crop they attack. Their numbers decline without their preferred food source. As you can see the benefits of a cover crop are numerous.

How to plant a cover crop?

Prepare the soil as you would if planting vegetables. Legumes will produce the nitrogen they need, but non-legume crops will need to have a nitrogen fertilizer added to the soil.

Inoculate legume seeds by moistening them, draining the excess water, adding the inoculant powder and mixing well.

Broadcast the seed evenly.

Cover seed with a thin layer of soil by raking in or going over the area with a rototiller set very shallow.

Keep the area moist until seedlings emerge. Light watering may be needed twice a day, or more in hot weather.

Mow and harvest cover crops before they flower and produce seeds, and till under at least 10 days to two weeks before planting garden crops.

Some recommended cool season garden cover crops are hairy vetch, Austrian winter peas, winter rye, winter wheat, crimson clover, red clover, white clover, yellow-blossom sweet clover, arrowleaf clover, ball clover, birdsfoot trefoil, fava bean, garden pea, barley, ryegrass, purple vetch, common/white vetch, alfalfa, oats.

Refer to the fact sheet entitled, Healthy Garden Soils (HLA-6436) for information regarding these cool weather cover crops. I chose to plant Austrian winter peas on some of the new terraces. The beds with a cover crop looked good all winter and yielded a successful summer garden. I have since planted a cover crop several years.