By The Old House Web


Cover crops are plants grown for their ability to maintain and rejuvenate the soil, rather than for their edibility. Cover crops perform a variety of useful functions, and are useful in many gardens. Cover crops reduce wind and water erosion by covering the soil with foliage and holding it in place with their root system. They minimize compaction and mineral leaching by reducing the impact of rain and runoff. Less weeds are able to establish themselves, because the cover crop aids in shading the weeds out.

The cover crop's top growth is called "green manure" and is a valuable source of organic matter when tilled into the soil. Other benefits to the garden result from the improvement in the granulation or texture of the soil provided by the increasing aeration and drainage that is a direct result of the cover crop's roots.

The ease of establishment varies with each cover crop. Grass-type cover crops are usually easier to establish than legumes such as clover, while larger-seeded crops such as oats establish more quickly than smaller-seeded crops. Planting time is critical. Many crops must be planted in late summer if they are to establish before fall, while others can be planted in earliest spring to develop a green manure crop before the garden is tilled for planting.

The following chart will be helpful in starting a cover crop:




Annual Rye Spr-Aug-Sept Annual High Moderate

Perennial Rye Aug-mid-Sept Perennial Moderate Moderate

Winter Rye Aug-Oct Biennial Moderate High

Oats Spr-Aug-Sept Annual Low Low

Winter Wheat Aug-Oct Annual Moderate High

Sweet Clover Summer Perennial Moderate High

White Clover Summer Perennial Moderate Low

Fescue Spring Perennial Moderate Low

Buckwheat Spr-Summer Annual Low Moderate (but reseeds)

--------------------------------------------------------- * Note that winter rye and rye grass grow very densely and shade out weeds more effectively than oats or legumes.

A large quantity of top growth may tangle with the rototiller when the crop is tilled in; this problem can be alleviated by mowing the area first and then rototilling. Rototilling will not kill perennial cover crops, consequently they may become a serious "weed" problem. One solution to this "weed" problem involves mowing the plot and broadcasting fertilizer as needed for the vegetable crop. The plot should then be covered with black plastic. The cover crop usually dies in about two weeks and vegetables may still be planted by making slits into the plastic and digging through small sections of the dead cover crop. This no-till method works well on average soils and actually minimizes soil compaction and deterioration.


Edited from an article by Nancy J. Butler in "Weed 'Em and Reap," Washtenaw County Cooperative (Oct-Nov '86 issue) Extension Service Publication, 4133 Washtenaw Road Ann Arbor, MI 48107

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