Gardening Articles: Landscaping :: Lawns, Ground Cover, & Wildflowers
Fall Garden Cover Crops (page 2 of 4)
by Charlie Nardozzi
But Not for Every Garden
Despite their many advantages, cover crops aren't always the ideal choice. Here are some considerations that may dissuade you from growing a cover crop.
Tilling Under. To gain the most benefits, gardeners should incorporate overwintering cover crops into the soil at or before full bloom in spring. Some crops, such as hairy vetch, put on so much top growth that you must cut or mow them before you turn them under. These may be difficult to handle unless you have a powerful mower, tractor, or tiller. With that equipment, the tops can be cut and tilled under, used as mulch around plants, or composted. Gardeners without such machines find it easier to grow cover crops that aren't winter-hardy in their areas or those that produce less top growth and are easy to turn under by hand in spring. Cover crops that die over the winter, including oats and mustard in the Northeast, still protect soil somewhat with their root systems.
Delayed Planting. Cover crops must be turned under in spring at least two weeks before planting. That requirement may delay your usual planting time if you have a wet soil or a wet spring, or if you're growing cover crops that mature later. Furthermore, you may have to till a cover crop in early, losing some benefits of nitrogen fixing and organic matter. If the tilled-in crop hasn't decomposed by planting time, your plants may have a temporary nitrogen deficiency as microbes use soil nitrogen to break down the organic matter from the cover crop.
Stealing Water. In dry areas, as in the Southwest, cover crops consume vital moisture from the soil, especially when they're getting established. In such situations, choose a crop such as barley that needs minimal water to germinate, grows well in dry soils, and is planted before annual rains in the area.
Weeds. If you allow some cover crops (annual ryegrass is one) to go to seed, they can become weeds. To derive maximum benefits from the cover crop and to prevent reseeding, till it under at or before flowering.