Submitted by Rick Thomason
Cover crops can be an important component to any home garden. They are used for various reasons, including building the soil, controlling soil erosion, and limiting the initiation and spread of certain diseases and insects in the soil. Cover crops are primarily used to “rest” or leave a garden area open during non-production times. Therefore, they are most often planted in the fall.
Leaving an unplanted area of your garden as bare soil can easily lead to the germination of unwanted weeds and to damaging soil erosion. Cover crops are intended to cover this bare soil and provide a cheap source of nutrition for your garden plants when cover crops are turned under and decomposed into the soil. They also increase the organic matter of the soil, as they break down into humus. Cover crops look more attractive than bare soil and, depending on the type of cover crops you plant, can attract beneficial and pollinating insects. Rotating between different vegetable families, as well as planting cover crops, can assist in starving out damaging soil pathogens by providing a non-host plant. Overall, the planting of cover crops is an essential organic method of protecting your garden, building better soil and increasing production.
Cover crops should be established after the summer garden fades, usually from early September into the first part of October. If you are not planning on planting a winter vegetable garden, you should consider seeding your entire garden in a cover crop. Try using a combination of a cereal grain with some type of legume. Typically, wheat, oats or rye is planted with a legume, such as clover or winter peas. Be sure you do not use ryegrass for a winter cover crop. Ryegrass is different than the cereal grain rye, and it is much too competitive and difficult to eradicate.
Legume crops have the added bonus of fixing atmospheric nitrogen, which can be used by the crops that follow when the legumes are tilled into the soil. This can help reduce your fertilizer expenses. A typical mix might be 3 to 4 pounds of a cereal grain with 0.25 pounds of a legume per 1,000 square feet.
Another important consideration is the use of a legume inoculant. Specific Rhizobia bacteria invade the roots of legumes, forming nodules where nitrogen fixation takes place. These bacteria are specific for different legumes and can be purchased to inoculate legume seed before planting. Inoculant comes in the form of a powder and is live bacteria. There are specific inoculants for various types of clovers and other legumes, so be sure to purchase the correct one. Sometimes the seed can be purchased that are already pre-inoculated. Nitrogen fertilizer should not be applied to legume cover crops as this interferes with nitrogen fixation; however, applications of phosphorus and potassium according to soil test recommendations can enhance nitrogen fixation.
Cover crops establish quickly when planted on a well-prepared seedbed. Prepare the bed by removing old vegetable plants and tilling the area to a depth of 4 or 5 inches. Seed can be broadcast over the intended planting area at the proper rate discussed earlier. It is best to test the soil before planting to determine the pH and fertility needs of your cover crop. Lime and fertilizer can be applied at the time of planting and should be tilled into the soil just before spreading seed. After the seed has been planted, lightly rake or drag the seed into the soil to establish good soil contact. Tiny seeds, such as clover, should not be buried deeply; make sure they are just barely below the soil surface. If you happen to have access to a roller or cultipacker, it is an excellent idea to go over the seedbed with such a tool to help firm the bed and increase germination.
Water the newly planted area every other day for the first week or two to assist in germination. Once the cover crop is up and growing, you can cut back watering to once a week.
*Source: University of Georgia Extension (Circular 1057), “Using Cover Crops in the Home Garden”