September 13, 2014

1 - Vetch and buckwheat are some cover crops that gardeners can use to improve their gardens.

Yard and Garden September 13, 2014


I have read about the benefits of planting a cover crop to improve garden soil. I would like to try it this fall. The soil is heavy clay typical of my location in Alamogordo. Can you suggest a crop or crops that would be beneficial to grow and then till under?

-Harold J. Schnell


There are several plants you can use in your garden for a fall cover crop. The vetches, especially hairy vetch, are used as nitrogen fixing cover crops. They are legumes, so if the seed are inoculated with the proper Rhizobium bacteria, they should add nitrogen as well as organic matter when turned into the soil. Hairy vetch is the hardiest of the vetch plants and may survive the winter in Alamogordo. If it has snow cover, it may survive for gardeners in even colder parts of the state.

Another common cover crop is buckwheat. This is fast growing and helps crowd out weeds. It does not supply nitrogen, but it produces green manure to improve soil organic matter content (for improved soil structure as well as improved water and nutrient holding capacity). Such increased organic matter would be beneficial in your clay soil. It is also known as a "smother crop" that smothers some weeds. It can be spring planted and tilled into the soil in the late spring. It will produce significant amounts of growth for green manure purposes in 4 to 6 weeks. There should be sufficient time for it to grow enough for a good cover crop in Alamogordo. To mature enough to produce seed requires 10 to 12 weeks. Buckwheat is frost sensitive and will probably not survive the winter in much of New Mexico.

In northern New Mexico time is becoming short, but for you in Alamogordo and gardeners in parts of the state with at least a month to a month and a half of growing season it should serve well as a cover crop. If the vetch cover crop overwinters or if you plant buckwheat in the spring, you can obtain significant growth before turning the cover crop into the soil to plant summer crops. The buckwheat may be allowed to grow into the summer to help manage some weeds, and then turned into the soil in late June or July to prepare for a fall garden.

Remember that the cover crop will require irrigation to develop properly. You should irrigate it as long as it is growing into the winter.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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