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Michael Wheeler: Winter cover crops are an investment for next summer
Michael Wheeler
Michael Wheeler, new director of Hall County Extension

True gardeners are planners. They always look ahead to next season on what to plant, where to plant and what to do differently from year to year. Sometimes looking ahead too far tends to make us forget what we need to do in the here and now.

There are a lot of different things that could be done this time of year, but using a winter cover crop in the vegetable garden is a good investment.

Cover crops are usually a grass like annual rye grass or legume, such as clover, planted on the existing garden site to help hold and build the soil.

There benefits of growing cover crops include:

reducing erosion;

improving soil structure and reducing surface crusting;

increasing the water-holding capacity of the soil;

reducing winter weed growth;

penetrating the hardpan in the winter, this improves plant root growth for the next crop;

providing nitrogen, if the cover crop is a legume.

Soil improvement through the use of a cover crop is a long-term investment. Cover crops will add organic content to the soil over time.

There are two general types of cover crops: legumes and nonlegumes. Legume cover crops, like vetch and clover, and add nitrogen to the soil. Nonlegume crops, such as wheat and ryegrass, are preferred on erosive soils.

Crimson clover is probably the most commonly used and most desirable of the clovers grown as a cover crop. It matures earlier and produces more nitrogen and dry matter sooner than most other clovers. On average, crimson clover can produce 30 to 50 pounds of nitrogen per acre.

Nonlegume cover crops (rye, ryegrass and wheat) have several advantages. They are less expensive to establish than legume cover crops. They also provide longer and better erosion control because of more winter growth and a fibrous root system.

The major disadvantage of nonlegume cover crops is that they do not fix nitrogen and usually require some nitrogen fertilizer when planted.

It is important to plant cover crops early to establish root growth before cold weather hits. This helps the crop better survive a hard winter. Plant legumes in mid-September to mid-October and plant grasses in early-October to mid-November.

A soil test from the office will accurately determine a cover crop’s need for lime, phosphate and/or potash. If lime, phosphate or potash are needed, apply them in the fall, just prior to preparing the seedbed.

If you are growing a legume cover crop, do not add nitrogen fertilizer. Treat the seed with the correct nitrogen-fixing bacteria (known as an inoculant). This inoculant is important to ensure good germination. Some seeds come pre-inoculated so ask your seed dealer which one you are buying.

Prepare the seedbed the same way you did for your spring garden. Either remove or till-in old crops. Work the soil while it is slightly moist, but not wet.

Grass type cover crops should be raked or dragged into a depth of a half-inch. Clover type cover crop seed is very tiny and should only be lightly raked to provide good soil contact, but not bury the seed.

Cover crops or green manures, as they are often called, are an economical way to both protect and build the soil. They are also aesthetically pleasing as they provide a nice green color, when most things are dormant. When spring arrives, till in the cover crop to help feed the summer garden.


Michael Wheeler is county extension coordinator for the UGA Cooperative Extension office in Hall County. You can contact him at 770-535-8293, His column publishes biweekly.

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