Ornamental · Polygonaceae
Buckwheat
Fagopyrum esculentum
Sow it in warm soil and buckwheat covers the ground, smothers weeds, and feeds the bees in a matter of weeks.
Full sun
Every 5–10 days
70–90 days
USDA 3–10
Overview
Buckwheat is one of the fastest plants you can put in the ground. Despite the name it has nothing to do with wheat, and it isn't even a grass. It's a broadleaf pseudocereal in the knotweed family, grown both for its triangular grain and as a quick summer cover crop. Within weeks of sowing it carpets bare soil with heart-shaped leaves and a haze of small white to pinkish flowers.
What it does best is buy time and tidy up the soil. A buckwheat stand smothers weeds before they get going, scavenges phosphorus and makes it more available to later crops, and draws bees and other pollinators in droves. One thing it doesn't do is fix nitrogen, since it isn't a legume, so gardeners pair it with a legume cover crop when they need that.
It asks for almost nothing and grows on poor, low-fertility ground that would starve fussier plants. The catch is its tender streak. Buckwheat wilts in heat and dies at the first frost, so it works as a warm-season filler between main crops rather than a year-round fixture.
Care
The short version: direct sow into warm soil after frost, give it light, well-drained ground that stays evenly moist, skip the fertilizer, and cut it down at early bloom before it sets seed.
Light
Buckwheat does best in full sun and will take partial sun without much complaint. More light means faster cover and better flowering, which is the whole point of growing it.
Water
Give it steady, even moisture, since buckwheat is not drought tolerant and wilts fast in hot, dry spells. At the same time it hates wet feet and fails on waterlogged or heavy soils, so the goal is moist but well drained.
Soil
It thrives on light to medium, well-drained loams and actually prefers low-fertility ground, performing poorly on heavy, wet, or high-lime sites. A pH anywhere from 5.0 to 7.0 suits it, and it tolerates poor and slightly acidic soil better than most crops.
Temperature
Buckwheat is a warm-season annual that runs from about 45°F to 95°F (7°C to 35°C). It's frost-tender, so a single cold night kills it, and it sulks in extreme heat.
Humidity
Ordinary outdoor humidity is all it needs, so there's no number to chase. It cares far more about cool, moist soil than about the air around it.
Feeding
Skip the fertilizer. Buckwheat is grown on low-fertility soils on purpose, and extra nitrogen just makes it flop over. It isn't a legume and fixes no nitrogen, but it does scavenge phosphorus and leave it more available for the next crop.
Pruning
When you're growing it as a cover crop, mow or till at early bloom, roughly 7 to 10 days after the first flowers open. That ends the crop before viable seed forms and keeps it from reseeding as a weed.
Repotting
none
Size & spacing
Plants reach 2 to 4 feet (60 to 120 cm) tall with a slim spread of 6 to 12 inches (15 to 30 cm). Because it's sown thickly as a stand rather than spaced out, that narrow footprint is what lets it knit together and shade out weeds.
When to plant
Buckwheat runs on warmth and has no tolerance for cold. Direct sow it in warm soil from late spring through midsummer once all danger of frost has passed, watch the flowers open within 3 to 6 weeks, and either terminate it at early bloom as a cover crop or harvest the grain at about 10 to 12 weeks, before the first fall frost ends it.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Not recommended; direct sow only.
- Plant: Direct sow in warm soil after all danger of frost has passed, late spring through midsummer.
- Harvest: Small white to pinkish flower clusters appear within about 3 to 6 weeks; grain harvested at about 10 to 12 weeks.
Hardiness
USDA hardiness zones: 3–10
Temperature: down to -40°C
Troubleshooting
Buckwheat has few real pests, so most trouble comes down to timing and weather rather than disease. Read the signs below, match them to what you're seeing, and act while it still helps.
Buckwheat keeps coming back as a weed in later plantings
This is volunteer reseeding, and it happens when a stand is left to flower and drop mature seed before you cut it down. The fix is timing. Mow or till at early bloom, about 7 to 10 days after the first flowers open and before any seed hardens, and hoe out the heart-shaped seedlings while they are still young.
Fix:
- Mow or till at early bloom, about 7 to 10 days after flowering begins, before any seed hardens
- Cultivate or hoe out volunteer seedlings while young
- Avoid letting any stand mature fully to seed
Plants blacken and collapse after a cold night
Buckwheat is a frost-tender warm-season annual, so a single cold or near-freezing night kills it outright and turns the foliage dark. There is no saving it once frost hits, so treat the kill as the natural end of the crop and work the residue back in. Sow only after frost has passed, and for grain, get it harvested ahead of the first fall frost.
Fix:
- Accept frost kill as the natural end of the crop and incorporate residue
- For grain, harvest before the first frost
Thin, weak stand in hot or dry ground
Buckwheat is not drought tolerant and wilts fast in midday heat, yet it also fails on heavy, waterlogged, or high-lime ground. The trick is to give it the middle path. Sow into light to medium, well-drained soil that holds steady moisture, and steer clear of both droughty and soggy sites.
Fix:
- Sow into adequately moist, well-drained soil
- Avoid heavy, wet, or droughty sites
No nitrogen boost for the crop that follows
This catches a lot of gardeners out, but buckwheat is a non-legume in the knotweed family and does not fix nitrogen from the air, no matter how lush it looks. Use it for what it actually does, which is smother weeds fast, scavenge phosphorus, and pile on quick biomass. When you need nitrogen, pair it with or follow it by a legume cover crop.
Fix:
- Use buckwheat for weed smothering, phosphorus scavenging, and quick biomass rather than nitrogen
- Pair or follow with a legume cover crop if nitrogen is needed
Toxicity
The grain is a wholesome, gluten-free food and the flowers are a prized honey and pollinator source, so for people the verdict is good. The caution is the green plant. Its flowers and foliage carry a pigment called fagopyrin, and grazing animals that eat large amounts and then stand in the sun can develop fagopyrism, a sunburn-like skin reaction. The seed itself holds none of it.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Caution
Cats rarely chew greens, but a cat that eats a good deal of the flowering plant can get an upset stomach, and the fagopyrin it takes in may leave light-colored or thin-furred skin sensitive to sun. Keep curious cats away from cut bouquets and standing plants in bloom.
Dogs Caution
A dog that nibbles the odd leaf is unlikely to suffer, but eating large amounts of the green, flowering plant can bring on a stomach upset. Watch pale-skinned or short-haired dogs for redness and itching on exposed skin after they have been out in the sun.
Horses Moderate
Grazing horses are at real risk, since heavy feeding on flowering buckwheat followed by time in the sun can trigger fagopyrism. The white-marked and lighter areas of the muzzle and legs blister, peel, and itch. Pull affected horses out of direct sunlight and off the plant.
Rabbits Moderate
Rabbits should not graze large amounts of the green plant. The fagopyrin in the foliage and flowers can make light skin and thin-furred areas, especially the ears, react to sunlight with inflamed, sunburn-like patches.
Livestock Moderate
Cattle, sheep, goats, and pigs are the classic victims of fagopyrism. Animals that graze a lot of flowering buckwheat and then stand in the sun develop swollen, blistered, itchy skin across their light-colored or exposed areas. Keep them off heavy stands in bloom.
Birds Caution
Birds eat the cleaned grain happily and it does them no harm, since the seed holds no fagopyrin. The caution is the green plant. Heavy feeding on the flowering tops could leave bare or pale-skinned birds sensitive to sun, so the risk sits with the foliage, not the seed.
People Grain safe
The hulled grain and buckwheat flour are a wholesome, gluten-free food and safe to eat. The only real caveat is the raw green plant: handling or eating a great deal of the flowering tops has, in rare cases, left light skin sensitive to sun, so the seed is the part people eat, not the foliage.
The cleaned grain and buckwheat flour are safe to eat. Keep pets and livestock from grazing large amounts of the flowering green plant, and be aware that affected light-skinned animals (and rarely people) should be kept out of direct sun after heavy ingestion.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
United Kingdom
Animal PoisonLine: 01202 509000 (fee applies)
Australia
Animal Poisons Helpline: 1300 869 738
Varieties
A few buckwheat types turn up again and again, whether you want grain, flour, or a fast cover crop. These are the ones worth knowing by name.
Common buckwheat (Fagopyrum esculentum)
This is the buckwheat almost everyone grows, a fast warm-season broadleaf with white to pinkish flowers and named cultivars like Mancan and Manor that serve for both grain and cover.
Tartary buckwheat (Fagopyrum tataricum)
A hardier cousin with small greenish self-pollinating flowers, this species shrugs off cold better and carries more rutin, though its grain tastes noticeably more bitter.
Silverhull
An old common-buckwheat type prized for milling, Silverhull carries silvery-gray, thin-hulled seed that grinds easily into flour.
How to propagate
Buckwheat couldn't be simpler to grow from seed, which is the only way most people start it.
SeedEasy
Direct sow in warm soil after all danger of frost, late spring through midsummer. · Germinates in about 3 to 5 days and covers the ground within a few weeks.
Buckwheat is almost always direct-seeded straight into the ground. Sow it into warm soil once all danger of frost has passed, any time from late spring through midsummer, and the seed breaks ground in just 3 to 5 days. From there it races to cover the soil within a few weeks, which is exactly how it smothers weeds so well.
Myths
Buckwheat is a kind of wheat or cereal grass and contains gluten.
The name misleads. Buckwheat is a broadleaf pseudocereal in the knotweed and smartweed family, with no tie to true wheat and nothing in common with cereal grasses. It is naturally gluten-free, which is why its flour suits people who can't eat wheat.