E.S. Oplinger1, E. A. Oelke2, M. A. Brinkman1, and K. A. Kelling1

1Departments of Agronomy and Soil Science, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison, WI 53706.
2Departments of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108.
November, 1989.

I. History:

Buckwheat (Fagopyrum sagittatum Gilib) has been grown in America since colonial days, and the crop once was common on farms in the northeastern and northcentral United States. Production reached a peak in 1866 at which time the grain was a common livestock feed and was in demand for making flour. By the mid 1960's the acreage had declined to about 50,000 acres. The leading buckwheat states are New York, Pennsylvania, Michigan, Wisconsin, Minnesota, and North Dakota. Canada has more buckwheat acreage than the United States.

Buckwheat enjoyed a resurgence of popularity in the mid 1970's that was brought on by the demand for commercially prepared breakfast cereal and by exports to Japan for making buckwheat noodles. This boom was due to the nutritional excellence of buckwheat. USDA-ARS analyses indicate that the grain has an amino acid composition nutritionally superior to all cereals, including oats. Buckwheat protein is particularly rich (6%) in the limiting amino acid lysine (Table 1).

Table 1. Average amino acid concentrations in buckwheat1.
Amino acid In seed In groat2 In protein
   ----------------------- % ------------------------
Glumtamic acid 1.99 2.72 18.02
Arginine 1.47 2.01 13.27
Aspartic acid 1.20 1.64 10.86
Valine 0.85 1.17 7.71
Leucine 0.75 1.02 6.75
Lysine 0.66 0.90 5.99
Glysine 0.61 0.83 5.52
Phenylalanine 0.46 0.63 4.17
Serine 0.46 0.62 4.12
Alanine 0.45 0.61 4.03
Threonine 0.43 0.58 3.87
Proline 0.41 0.55 3.66
Isoleucine 0.39 0.53 3.48
Tyrosine 0.23 0.32 2.12
Histidine 0.23 0.32 2.11
Cystine 0.18 0.25 1.66
Methionine 0.15 0.21 1.37
Tryptophan 0.14 0.19 1.29
1From Robinson, R.G., The Buckwheat crop in Minnesota,Agricultural Experiment Station Bulletin 539, 1980.
2Calculated from analyses of whole seed.

II. Uses:

Until the recent increased interest in buckwheat for human food, about 75% of the grain produced was used for livestock and poultry, about 5-6% for seed, with the remainder milled into buckwheat flour. Between 5 and 10% of the seeded acreage was turned under for green manure. Several thousand acres were arvested green for extracting rutin. Today, the major use of buckwheat is for human food. The composition of buckwheat grain and its byproducts, are shown in Table 2. The amino acid concentrations, as reported by Robinson, are shown in Table 1.

Table 2. Percent composition of buckwheat grain and buckwheat by products1
Grain or byproduct Moisture Protein Fat Fiber N-free extract Ash
  ------------------------ % -----------------------
Whole grain 10.0 11.2 2.4 10.7 64.0 1.7
Flour, light 12.1 7.8 1.5 0.7 76.7 1.2
Flour, dark 11.7 15.0 2.8 1.1 67.7 1.7
Groats 10.6 11.2 2.4 0.6 73.7 1.5
Hulls 8.0 4.5 0.9 47.6 36.8 2.2
Middlings 10.7 27.2 7.0 11.4 39.1 4.6
Farina 12.0 2.7 0.4 0.4 83.0 0.5
1 From Coe, M. R. Buckwheat milling and it by-products. USDA Circular 190. 1931.

A. Food for Humans:

Most of the buckwheat grain utilized as food for humans is marketed in the form of flour. The flour is generally dark colored due to presence of hull fragments not removed during the milling process. Buckwheat flour is used primarily for making buckwheat griddle cakes, and is more commonly marketed in the form of pancake mixes than as pure buckwheat flour. These prepared mixes may contain buckwheat mixed with wheat, corn, rice, or oat flours and a leavening agent. Buckwheat flour is never produced from tartary buckwheat because of a bitter taste that makes it undesirable as human food.

Some buckwheat grain is utilized in the form of groats (that part of the grain that is left after the hulls are removed from the kernels). The product may be marketed as whole groats, cracked groats, or as a coarse granular product. These products are used for breakfast food, porridge, and thickening materials for soups, gravies, and dressings.

Buckwheat may cause a rash on the skin of certain individuals, especially if it is eaten frequently or in large quantities.

Buckwheat flour and groats must be used fresh because their fat content is high and they soon become rancid. This poor keeping quality makes buckwheat products difficult to handle in the summer.

B. Feed for Livestock:

Buckwheat is a satisfactory partial substitute for other grains in feeding livestock. It has a lower feeding value than wheat, oats, barley, rye, or corn. The grain should be ground and mixed with at least two parts of corn, oats, or barley to one part buckwheat.

When fed continually or in large amounts to certain animals, buckwheat grain may cause a rash to appear on the skin. This rash is confined to the white-haired parts of the hide of the animal, and apparently occurs only when animals are exposed to light. The substances that produce the rash are in the buckwheat hulls.

Tartary buckwheat has a lower feeding value for livestock than the common varieties, but it was used extensively as an ingredient of scratch feeds for poultry. The small, smooth, rounded seed of tartary makes it more satisfactory for poultry than the larger and more angular seeds of common buckwheat.

Buckwheat middlings are rich in protein, fat, and minerals, and are considered a good feed for cattle when not fed in large amounts or as the only concentrate. They may also be used satisfactorily as a substitute for linseed meal in a ration consisting of tankage, linseed meal, and alfalfa hay. Buckwheat middlings apparently have no harmful effect on dairy cows or dairy products. They are not satisfactory for pigs when fed as the only concentrate, and are not palatable to pigs as are other ground grains.

Buckwheat hulls have little or no feeding value, but they contain most of the fiber of the seed. They are sometimes combined with middlings and sold as buckwheat feed or bran. They are also used as soil mulch and poultry litter in the U.S. and for pillow stuffing in Japan.

Buckwheat straw is sometimes used for feed when well preserved, but may cause digestive disturbances when fed in large amounts.

Buckwheat seed is an ingredient in commercial bird feed mixes and the seed is sometimes planted to provide feed and cover for wildlife.

C. Honey Crop:

With the exception of tartary, buckwheat is sometimes used as a honey crop. It has a long blooming period, especially in September when other sources of nectar are limited. The honey is dark in color, and has a strong flavor unpleasant to some persons but highly favored by others. Buckwheat was once an important honey crop in this country, especially in the Northeast where climatic conditions are most favorable to nectar flow. When buckwheat was commonly grown, it was one of the beekeepers' greatest sources of nectar, and the supply of buckwheat honey generally exceeded the demand. However, because of the decline of buckwheat as a grain crop, buckwheat honey now is so uncommon that it may command a price higher than that of almost any other honey.

Buckwheat nectar flow is favored by adequate moisture combined with clear, still days and cool nights. Under these conditions, an acre of buckwheat may support a hive of bees and yield up to 150 pounds of honey in a season. Reports are that it is not uncommon for a strong colony to glean 10 pounds of honey per day while foraging buckwheat. Although buckwheat is one of the most dependable and highest yielding honey plants, it normally yields nectar only during the morning and bees are unable to complete a full day of nectar collection. As a result, bees working buckwheat may not be very amiable to the beekeeper should he visit his hives in the afternoon.

Buckwheat may fill a special need for the beekeeper since the honey flow comes late in the season when other nectar is scarce. Thus, it may be possible to obtain a crop of buckwheat honey in an area where an earlier flow has been harvested from other sources. The variety Tokyo is reported to produce a lighter colored honey than most buckwheats.

D. Smother Crop:

Although modern weed control methods have reduced the need for smother crops, buckwheat may still be useful for this purpose. Buckwheat is a good competitor because it germinates rapidly, and the dense leaf canopy soon shades the soil. This rapid growth soon smothers most weeds.

Buckwheat has been cited as a useful crop for control of quackgrass in the northeastern states, but rapid and complete control should not be expected. A heavy crop of buckwheat should smother most of the quackgrass if the land has been previously cultivated to break up the quackgrass sod, and then fall- or early spring-plowed and disked or field cultivated occasionally until planting time.

Other weeds may be more effectively controlled by growing buckwheat. Scientists have reported that the crop can be used to eradicate Canada thistle, sowthistle, creeping jenny, leafy spurge, Russian knapweed and perennial peppergrass (Marshall and Pomeranz).

Because of buckwheat's early competitiveness, it is not useful as a companion crop for establishing legumes.

E. Green Manure Crop:

Buckwheat is a useful green manure crop. It can produce significant amounts of dry matter. Up to 3 tons of dry matter per acre has been obtained after 6 to 8 weeks of growth on relatively unproductive land under Pennsylvania conditions. When plowed under, the plant material decays rapidly, making nitrogen and mineral constituents available for the succeeding crop. The resulting humus improves physical condition and moisture-holding capacity of soil. Where a second crop of green manure is desired, rye may be drilled into the buckwheat stubble and plowed under in the spring. The rye frequently can be drilled into the buckwheat stubble without previous disking or plowing.

Buckwheat green manure may also fit into fairly tight rotations such as when a crop is harvested prior to mid-July and a succeeding crop is not scheduled until fall. If volunteer buckwheat is harmful in the succeeding crop, then the green manure crop of buckwheat should be destroyed before a large number of seeds mature.

F. Milling Buckwheat:

A few mills still use old-fashioned stone burs to produce buckwheat flour, but the greater number use steel rolls. Some buckwheat flour is milled so finely and is so refined that it is as white as wheat flour. Usually, however, small particles of hull remain in the flour and give it a characteristic dark color. Flours are milled to meet the protein and fiber specifications of the buyer.

One hundred pounds of clean, dry buckwheat yields 60 to 75 pounds of flour, 4 to 18 pounds of middlings, and 18 to 26 pounds of hulls. Not more than 52 pounds of pure white flour from 100 pounds of grain is obtained in milling. Buckwheat more than 1 year old is reported to make flour inferior to that made from freshly harvested grain. The middlings, composed mostly of the germ and the inner covering of the grain just beneath the hull, are used for feed.

III. Growth Habits:

Buckwheat has an indeterminate growth habit. Consequently the plant grows vegetatively and flowers until terminated by frost. There has been little effort to improve the crop through plant breeding since buckwheat is naturally cross-pollinated and cannot be inbred because of self-incompatibility. Therefore, buckwheat yields, unlike those of other crops, have remained relatively stable and thus have discouraged production. Flowers of cross-pollination species of buckwheat attract insects because of their secreted nectar. However, studies at Pennsylvania indicate that insect activity is not essential to get effective fertilization and seed set.

IV. Environment Requirements:

A. Climatic Requirements:

Buckwheat grows best where the climate is moist and cool. It can be grown rather far north and at high altitudes, because its growing period is short (10 to 12 weeks) and its heat requirements for development are low. The crop is extremely sensitive to unfavorable weather conditions and is killed quickly by freezing temperatures both in the spring and fall. High temperatures and dry weather at blooming time may cause blasting of flowers and prevent seed formation. Generally, buckwheat seeding is timed so that the plants will bloom and set seed when hot, dry weather is over. Often seeding is delayed until three months prior to the first killing frost in the fall.

B. Soil Requirements:

Buckwheat grows on a wide range of soil types and fertility levels. It produces a better crop than other grains on infertile, poorly drained soils if the climate is moist and cool. It is an efficient crop in extracting phosphorous of low availability from the soil. In addition, buckwheat tends to lodge badly on fertile soils. It is often better suited than most other grains on newly cleared land, on drained marsh land, or on other rough land with a high content of decaying vegetative matter.

Buckwheat has higher tolerance to soil acidity than any other grain crop. It is best suited to light to medium textured, well-drained soils such as sandy loams, loams and silt loams. It does not grow well in heavy, wet soils or in soils that contain high levels of limestone. It grows well where alfalfa or red clover would not. On soils high in nitrogen, lodging may occur and cause a reduction in yield. Once lodged, a buckwheat plant does not return upright. Crusting on clay soils may result in an unsatisfactory stand because of poor seedling emergence.

C. Seed Preparation and Germination:

Buckwheat will germinate at temperatures ranging from 45o to 105oF. Freshly harvested seed of some types may not germinate until after 30-60 days of drying and storage. The seed may retain its viability for several years, but seed that is no more than one year old is best to use for planting. Buckwheat plants will emerge from the soil 3-5 days after planting. The time required is influenced by depth of seeding and the temperature and moisture content of the soil.

V. Cultural Practices:

A. Crop Sequence and Rotation:

Serious diseases affecting other dicot field crops have not been important in buckwheat; therefore the volunteer plant problem is the main problem in crop sequences. Volunteer sunflower, rapeseed, mustard, and corn can be serious weeds in buckwheat planted before June 15. Volunteer buckwheat can be a problem in crops following buckwheat, but herbicides will control these in most crops.

B. Seedbed Preparation:

A firm seedbed is best for successful buckwheat production because of its relatively small seed size and its shallow root system. A firm seedbed facilitates absorption of nutrients essential for rapid growth, and tends to reduce losses from drought. If soil has been plowed for a previous crop which has failed, only disking or harrowing may be required. Rolling or cultipacking the seedbed just prior to seeding is sometimes helpful.

C. Seeding Date:

Buckwheat may be sown at any time after all danger of killing frost is past. Since the crop grows rapidly and matures in a short growing season, the most common practice is to seed the crop only 10-12 weeks before a killing frost is expected. For Wisconsin, seeding in mid-June is advised. For Minnesota, plantings in June in the north, before July 15 in the central, and before July 25 in the extreme southern part of the state may mature sufficiently before normal frost dates. The crop produces seed within one month after planting and continues to flower and produce seed until killing frosts occur.

D. Method and Rate of Seeding:

The most satisfactory method of sowing buckwheat is with a grain drill that plants the seed one to two inches deep. Poor stands are likely when seedings are more than two inches deep.

A seeding rate of 36 to 72 pounds per acre or 16 seeds per square foot of clean, viable seed is sufficient. At least 48 pounds per acre should be used of large-seeded varieties such as Pennquad.

Thin stands of buckwheat produce strong plants that branch and resist lodging on good land. Thick stands produce plants that are spindly and have short branches and poor seed set.

E. Fertilizer and Lime Requirements:

Buckwheat has a modest feeding capacity compared to most other grains, and if fertilizer is not applied, the removal of nutrients by a buckwheat crop may have a depressing effect on the yield of the following crop. Typical nutrient removals by the grain for a 1200 lb/a crop are 9 lb/a N, 3 lb/a P2O5 and 12 lb/a K2O. However, in Minnesota, a 2000-pound yield of seed removed 40 pounds N, 20 of P2O5 and 13 pounds per acre of K2O or about the same as a 2000 pound crop of sunflower seed. The crop grows well on acid soils and gives little response to liming above a pH of 5.0. It has about the same acid tolerances as oat and potatoes. Soils should be limed for the crops grown in rotation with buckwheat.

It is unlikely that buckwheat will respond to additional P or K at soil tests above 30 lb/a P or 300 lb/a K. Table 3 shows the recommended fertilizer rates for buckwheat yielding 30-50 bu/a for Wisconsin and Minnesota.

Table 3. Wisconsin and Minnesota recommended fertilizer applications for a goal of 30 to 50 bu/a buckwheat yield.
Soil Test N1 P205 K2 O
  ---------------- lb/a ---------------
Very Low or Low 30 60-80 60-90
Medium 30 30-40 30-60
High 30 15-20 15-30
Very High or Excessively High 30 0 0
1 Recommended nitrogen rate ranges from 0 to 50 lb N/a depending on cropping history and organic matter level. If the previous crop was alfalfa, no nitrogen is recommended. If the previous crop was corn or small grains the recommended
nitrogen rate is 50 lb N/a where soil organic matter is <2%, and 15 lbs N/a where the organic matter is 2-5%.

F. Variety Selection:

Because little breeding work has been done on buckwheat, there are only a handful of varieties that are grown in the United States. Dr. Harold Marshall, formerly with the USDA at Penn State University did much of the variety improvement work in the 1960's to 1980's. The tetraploid variety Pennquad was released by Dr. Marshall's program in 1966 and is still grown on some of the buckwheat acreage. Most of the available buckwheat varieties are diploids. Since buckwheat is cross pollinated, variety designations may not be valid except for Certified seed lots. Varieties that have been grown in the United States in the past 20 years include:

Mancan: Large-seeded diploid variety. Has low test weight but good market acceptability. Released by Agriculture Canada and licensed in 1974.

Manor: Large-seeded diploid variety. Has low test weight but good market acceptability. Released by Agriculture Canada and licensed in 1980. Production of certified seed is limited to Canada.

Pennquad: Very large-seeded tetraploid variety. Has good lodging resistance. The grain is especially well suited for milling because of its large, uniform size. Released by the Pennsylvania Agricultural Experiment Station in 1966.

Tempest: Small-seeded diploid variety with high test weight. Selected by Agriculture Canada from a Russian seedlot and licensed in 1971.

Tokyo: Small-seeded diploid type with high test weight. Developed by Agriculture Canada from a Japanese introduction.

Winsor Royal: Large-seeded diploid type with low test weight, but has good market acceptability. Released by Winsor Grain Company, Minneapolis, Minnesota, in 1982. Sale of seed is regulated by the U.S. Variety Protection Act.

Common: Seed lots tested under this name range from small to medium in seed size and often have medium to high test weight.

G. Weed Control:

1. Mechanical: The best means of controlling weeds is to destroy the young weed seedlings with tillage prior to planting buckwheat. Good, solid stands of buckwheat will compete with weeds which may germinate later.

2. Chemical: There are no herbicides registered for use on buckwheat in Wisconsin or Minnesota.

H. Diseases and Their Control:

Diseases are not a problem in buckwheat production, although a leaf spot caused by species of the fungus Ramilaria and a root rot caused by Rhizoctonia sometimes occur.

I. Insects and Other Predators and Their Control:

Wireworms and aphids may attack buckwheat, but do not cause serious losses. Japanese beetles are particularly fond of buckwheat flowers and may occasionally do considerable damage.

When birds are numerous, they may do considerable damage to buckwheat grain before the crop is ready for harvest. Deer and other wildlife may also damage buckwheat if the field is adjacent to a wooded area or other cover for wildlife. Rats and mice can be very destructive in buckwheat fields, especially when the plants have lodged.

J. Harvesting:

The best practice is to direct combine when the maximum number of seeds have matured (75% of seed brown or black) and the plants have lost most of their leaves. When immature plants are harvested, green seeds and moist fragments of the plants may cause difficulties in storing the grain. However, considerable grain loss from shattering may occur if the crop is left standing, especially after a killing frost.

Cylinder speed (about 650 RPM) and cylinder concave clearance (1/8-1/2 in.) of the combine should be set to prevent excessive cracking and breaking of the grain. Losses and broken kernels should be checked to refine combine adjustments.

Proper selection of the sieves and adjustment of the chaffer and air settings are also important to insure minimal losses. Sieve openings of 1/4 to 3/8 in. are suggested.

K. Drying and Storage:

Grain harvested with a combine may contain green plant fragments and require careful drying for safe storage. Drying of buckwheat grain prior to cleaning facilitates the removal of plant fragments and immature seeds. Seed should be dried prior to storage if its moisture percentage exceeds 16. With the use of a grain drier, buckwheat can be harvested at a much higher moisture content, thus minimizing the loss due to shattering. Market grades have been established for buckwheat and discounts are common if the seed doesn't meet the grade standards.

VI. Yield Potential and Performance Results:

Buckwheat yields in Wisconsin and Minnesota typically range from 500 to 2,000 pounds/acre. With good management and favorable weather, buckwheat should yield 1,200 to 1,600 pounds/acre in a cool, moist climate that is common in northern Wisconsin or Minnesota. No yield trials have been conducted in Wisconsin in recent years. Performance of three buckwheat varieties in 23 tests in Minnesota from 1982 through 1987 is summarized in Table 4.

Table 4. Performance of buckwheats in Minnesota tests, 1982-87.
Variety Yield
Test Weight
Days to
first bloom
No. of Seeds
per lb
Mancan 1003 44 32 40 15,770
Manor 1070 44 32 40 16,256
Winsor Royal 1124 44 32 40 15,230

VII. Economics of Production and Markets:

The profitability of growing buckwheat today is quite variable. Buckwheat has not been grown extensively in recent years because other crops were more profitable. Before planting buckwheat, growers are urged to ask themselves the following questions:

1. Where will I purchase good quality seed? 2. What will be the seed price? 3. For what purpose will I raise the crop? – for feeding to livestock on my own farm? - to sell as a cash crop? - to be used personally for food? - to be left for wild game feed? 4. If I plan to sell, is there a buyer in the area? What price will I receive if I sell? Are there quality requirements? 5. If I plan to use it for food, how will I process it?

VIII. Information Sources:

Buckwheat Culture. 1956. W. J. Sandra. Farmers Bulletin No. 2095, USDA.

Description and Culture of Buckwheat. 1969. H. G. Marshall. Bulletin 754, Pennsylvania Agr. Exp. Sta.

Millet, Buckwheat and Annual Canarygrass Production in Minnesota. 1962. R. G. Robinson. Bulletin 302, Minnesota Agr. Exp. Sta.

Varietal Trials of Farm Crops. 1989. Minnesota Report 24, Minnesota Agr. Exp. Sta.

Buckwheat: Description, Breeding, Production, and Utilization. 1982. H. G. Marshall, and Y. Pomeranz. Advances in Cereal Science and Technology 4:157-210.

Buckwheat Production in Wisconsin. 1988. E. S. Oplinger and M. A. Brinkman. Field Crops 32.9. Univ. of Wis. Agronomy/UWEX mimeo. February 1988. 10 p.

Soil Test Recommendations for Field, Vegetable and Fruit Crops. 1981. K. A. Kelling, P. E. Fixen, E. E. Schulte, E. A. Liegel, and C. R. Simson. UWEX Bull. A2809. Univ. of Wisconsin-Madison. 53706.

The Buckwheat Crop in Minnesota. 1980. R. G. Robinson. Bulletin 539. Agric. Exp. Sta., Univ. of Minnesota, St. Paul. 55108.

Guide to Computer Programmed Soil Test Recommendations for Field Crops in Minnesota. 1986. G. W. Rehm, C. J. Rosen, J. F. Moncrief, W. E. Fenster and J. Grava. Ag. Bu. 0519. Minnesota Extension Service, Univ. of Minnesota, St. Paul. 55108.

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