Quick cover crop for weed control
By Lynn Byczynski
Buckwheat is one of the easiest and quickest cover crops, used primarily to suppress weeds and improve soil tilth. It is a warm-weather crop that can be used between spring and fall vegetables or in preparing new ground — when planted on newly prepared sod ground, buckwheat will help rot down the sod — for vegetable or berry production in fall or the following year.
Buckwheat is an attractive plant, 2' to 4' tall with triangular leaves and flowers of white, pink, or red. Buckwheat germinates within days of seeding and does best at a soil temperature of at least 55F/12.8C. It begins to flower in four weeks and is a source of nectar for honeybees and native pollinators. Seed matures two to three weeks after flowering and, if left in the field, is a food source for ground-dwelling birds such as quail and pheasant. Buckwheat will be killed by light frost. It does not provide nitrogen nor does it increase soil organic matter significantly, but it does improve soil condition in the top few inches, a benefit for vegetable seeds and transplants.
The key to using buckwheat for weed control is to provide the optimum conditions for getting it up and growing so that it will be ahead of weeds. Here are some tips for getting a strong stand and managing it for improved vegetable production in the future:
- Till in any weeds or plants from a previous crop and wait one week for the debris to decompose sufficiently for the buckwheat seed to germinate. Break up big clumps of soil, and create the finest seedbed possible.
- Let the soil warm up and dry out if it's been wet. Buckwheat seed rots easily in cold, wet soil. If the soil is extremely dry, irrigate to a depth of 1" before planting.
- Buckwheat seed should be barely covered with soil for best germination. Do not plant too deeply, but don't leave the seed exposed on the soil surface either. Buckwheat seed can be hand-broadcast at a rate of 60 lb. per acre if care is taken to spread it evenly. Or it can be drilled to a depth of less than 1 inch at a rate of 50 lb. per acre. If there is heavy weed pressure or you are planting organic buckwheat seed, you may want to increase the rate to about 80 lb. per acre.
- As the seed germinates, check for gaps in the stand, and reseed any that are more than 1' in diameter. If weeds are allowed to grow in these empty areas, they will produce seeds that continue the weed cycle, and the benefits of the buckwheat will be reduced.
- The plants should start to flower about four or five weeks after seeding. If the land is needed for a fall crop, mow the buckwheat before the seeds mature. If the land won't be needed until the following year, the buckwheat can be left to reseed and a second crop can be grown in the same season. However, buckwheat will not overwinter, so it should be mowed and replaced with a winter cover crop in late summer or fall.
For more information
• Oregon Cover Crops: Buckwheat, by Oregon State University Extension
• Cover Crop Database: Complete Crop Summary of Buckwheat, by University of California Sustainable Agriculture Research and Education Program
• Buckwheat Cover Crop Handbook, from Cornell University
Lynn Byczynski is the editor of Growing for Market and the publisher of The Hoophouse Handbook.