By Jean English
Keeping a vegetable garden is like keeping a family: Both need continuous care and nourishment if you want them to thrive. In the case of the garden, that means keeping up the weeding and/or mulching now, and keeping bare spots planted. If you’ve planted all of the lettuce, spinach, carrots and other crops needed to nourish your family and you still have space available, you could plant one of the garden’s best friends: buckwheat (Fagopyrum esculentum).
Native to Central Asia, this broadleaf, non-leguminous, frost-sensitive green manure is ideal to plant in Maine gardens from late May through July. It grows fast then, quickly forming a weed-shading cover, and thus is termed a “smother crop.” It grows so quickly, in fact, that you can fit two crops of this annual plant into one summer if you have an especially weedy area that you want to “herbicide” in a friendly way.
To grow buckwheat, broadcast a cup of seed over 100 square feet (or 1 pound per 300 to 500 square feet; or 60 to 80 pounds per acre) and rake it in about an inch deep. It will sprout, grow and begin to bloom within six weeks – without any added fertilizer. At that time, or when the crop is about 8 inches tall, till it in. At this stage the stems will still be succulent and not too fibrous, so they’ll be easy to incorporate into the soil and will rot quickly, leaving a good seedbed.
As it grows, buckwheat has the added attraction of being unusually good at extracting and accumulating phosphorus from sources that are usually quite insoluble, such as raw rock phosphate. Thus, if your soil is low to moderate in phosphorus, buckwheat can help extract some of this existing phosphorus or solubilize phosphorus in added rock phosphate and increase the amount of this nutrient that is available to subsequent crops. Buckwheat also takes up other nutrients, such as nitrogen and potassium, that could otherwise be lost by leaching out of or running off of bare soils.
In addition, buckwheat improves soil aeration and structure, promotes microbial growth, and helps retain soil moisture. It’s reputed to loosen clay soils – possibly due to the breakdown of organic matter after it’s tilled in, since its root system is not exceptionally deep or extensive. The crop will grow on most soils, but does best on well-drained soils. It is more tolerant of acid soils than any other grain crop.
Buckwheat blooms over a period of time, rather than all at once. For this reason, gardeners usually are advised to till the crop in as soon as it starts to bloom; otherwise, seeds will be produced, will ripen over time and could contribute to turning the smother crop itself into a weed. If you want to let the flowers bloom for a short time, however, the bees will appreciate them. They visit the small, white, fragrant flowers with vigor, then go home and make buckwheat honey. Beekeepers appreciate buckwheat as a honey crop because it flowers for a month or more, and an acre of these flowers provides enough nectar to produce 100 to 150 pounds of honey. Other beneficial insects, such as syrphid flies, are attracted to buckwheat flowers as well.
You might want to let the plants go to seed in order to save your own seed. Since the seed matures at different rates and you want to minimize the buckwheat-as-a-weed problem, harvest the plants when about 75% of the seeds are brown. Pull the plants, or cut the stems at ground level, leaving the roots in the soil. Pull off the seed tops and let them dry in open paper bags or on a screen. When they’re dry, rub them between your hands to loosen the seeds. Then pour the seeds back and forth, from one bucket to another, several times in a light breeze or in front of a fan to separate the chaff from the grain. You can use this seed for planting later; it’s good for three years. Dehulling buckwheat seed for eating requires special equipment.
Can you fit buckwheat into your garden? Consider planting it between corn rows, after strawberry harvest (the straw can help mulch the strawberry plants over winter), or after peas or other early vegetables are removed. Scatter it among tall-growing annual crops at a rate of about 1 ounce per 50 square feet. The residue from late-planted buckwheat can help catch snow and reduce erosion over winter.
Grow a plot for your animals: Chickens, rabbits and livestock all like buckwheat and can be fed the grain and straw. Watch out, though: Deer and wild birds also like the crop.
If you time it right, you can fit in a crop of weed-smothering buckwheat this summer and follow it with an overwintered green manure/cover crop of hairy vetch and rye, adding abundant organic matter and nitrogen to the soil to nourish your garden next year. Eliot Coleman suggests one possible rotation to prepare a fertile garden bed: Seed winter rye in the fall; undersow it with biennial sweet clover the following spring; mow the rye in midsummer; let the sweet clover grow through the winter; mow the clover the second summer and follow it with buckwheat; mow the buckwheat in the fall and sow a rye-hairy vetch mix; till this in in the spring and plant vegetables. The mowed cover crops can be used to make compost.