Cover Crops

by Karen Weiland, Advanced Master Gardener

If you would like to increase the amount of organic matter in your garden soil, planting a cover crop would be a good beginning.  A cover crop can be Cover Crop Seedssmall grains, legumes or grasses and are usually planted in the fall and then tilled under in the spring.  They also prevent erosion, fix nitrogen into the soil and aid in the supression of the weed population (something I’m sure we would all like).

During the summer, continuous crops of buckwheat can be planted where early vegetable crops have been harvested.  Till the soil before planting the buckwheat seed, which will germinate quickly and prevent any weeds from becoming King of the Garden.  Buckwheat grows and flowers in only six weeks and needs to be tilled under before it goes to seed.  It adds calcium, phosphorus and potassium to the soil and likes the heat of the summer.

Winter rye is planted and grows in the fall, the roots survive the winter and the plant will begin to grow again in the spring.  Winter rye absorbs nitrogen and holds onto it until the rye is tilled under at which time the nitrogen is released to be absorbed by the garden plant.  Two cover crops that work well together are winter rye and hairy vetch.  The rye shades out the weeds and the vetch fixes nitrogen in the soil.  Vetch has deep tap roots that help to loosen and improve the soil.

Spring CloverCover crops that are tilled under for the purpose of improving the soil are sometimes called green manure.  Legumes like mammoth red clover, crimson clover, hairy vetch or bell beans will gix nitrogen in the soil and add organic matter when they are tilled under in the spring.  Dutch white clover is a legume that can be planted and used as a living mulch between rows.  Not only does it add nitrogen to the soil, it can be walked on, it will keep the weeds at bay and it’s flowers will attract pollinating friends to your garden.  The following spring the clover can be tilled under, garden crops planted where the clover had been and a new batch of clover can be planted in the row where the garden crop had been for a simple way of crop rotation.

In past years I have waited too long to purchase my cover crop seed and have had to do without.  Just recently I picked up a bag of Spring Green Mix at a local nursery.  It contains seeds of crimson clover, cereal rye and something called Groundhog radish.  I inquired about the groundhog radish and to whether that was  the cover crop I had seen in many a garden last year.  After checking photos on the internet I am sure that was what I had seen and decided I needed to give it a try.

The mix I purchased can be planted from August to October.  Since radishes are in this mix it is best to sow this mix early enough to allow 6 weeks of growth before regular frosts occur. Radish are tolerant of a light frost but will winter-kill when the temperatures fall into the twenties. I feel the need to tell you that rotting radish residues produce a nasty rotten egg-like odor, particularly during winter thaws.

Radishes germinate quickly, emerging within three to four days under optimal conditions.  Seed that has been broadcast on the surface can establish Radisheswell if it is followed by rainfall or irrigation.  These radishes are not your typical, small slice and eat radishes.  These babies get big, with the roots extending to about three feet in sixty days.

Bare soil in the garden is an open invitation for weeds to come in and take over.  Take the time to plant a cover crop.  It will make your garden smile.  Talk with your local extension agent or farm supply store manager to find out what would best meet your needs for a cover crop.

As always, Happy Gardening!

More information about gardening and related subjects is available online at The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange Co, 636-2111 in Noble Co., 925-2562 in DeKalb Co. and

668-1000 in Steuben Co.