Gardeners have long used certain plants known as cover crops to help keep soil from blowing away during winter. An added benefit of raising cover crops is that their foliage and root growth can be tilled under in late winter to help loosen heavy soils and improve overall soil structure and fertility.
Cover crops generally are sown in late summer or early fall, after summer vegetables are harvested. The type of plant you grow will depend on the desired function as well as availability. Winter rye, buckwheat, hairy vetch, and winter wheat are ideal for use as cover crops, and are among the most commonly available through garden centers and mail-order catalogs.
The amount of seed to plant will vary with the species, but in general, winter cover crops are seeded at a rate of 2 to 3 pounds per 1,000 square feet. Till or spade the soil and scatter the seed over the area to be covered at a depth corresponding to the size of the seed. Large seeds should be covered with .25 to .5 inch of soil or compost. Small seeds can be left on the surface and lightly raked. Apply a thin layer of loose straw to protect the area from wind and runoff from heavy rains.
Fertilizing is generally not necessary, especially for established garden beds. Some members of the legume family of plants, most notably alfalfa and hairy vetch, actually facilitate the fixing of nitrogen in association with certain soilborne bacteria. The bacteria colonize in nodules of the legume’s roots.
The root growth of the cover crops will help loosen heavy clay or otherwise compacted soils, and the addition of the dead foliage later in winter or spring will improve aeration, water-holding capacity, and nutrient status. The cover crop should be plowed under several weeks prior to spring planting to allow the vegetation a chance to break down a bit. Then till the soil again immediately before planting the garden.