Ornamental · Polygonaceae
Buckwheat
Fagopyrum esculentum
Tuck the seed into warm ground and within a few weeks buckwheat spreads a low sheet of heart-shaped leaves, crowds out weeds, and lifts pale flowers loud with bees.
Full sun
Every 5–10 days
70–90 days
USDA 3–10
Overview
Buckwheat is among the fastest plants you can set in the soil. The name is deceptive, because it has nothing to do with wheat and is not even a grass. Up close it is a broadleaf pseudocereal in the knotweed family, grown both for its small triangular grain and as a quick summer cover crop. Within weeks of sowing, it lays a low blanket over bare ground, all heart-shaped leaves and a thin haze of small white to pinkish flowers.
Its best work is buying time and cleaning up the soil. A stand smothers weeds before they can take hold, pulls phosphorus up and leaves it more available to later crops, and pulls in bees and other pollinators by the swarm. One job it cannot do is fix nitrogen, since it is no legume, so gardeners pair it with a legume cover crop when that is what they want.
It asks for next to nothing and takes to poor, low-fertility ground that would starve choosier plants. The weak point is its tenderness. Buckwheat wilts in heat and dies at the first frost, so it serves as a warm-season filler between main crops rather than a standing fixture.
Care
The short version: press seed into warm earth after the frosts, give it a sunlit, sharply drained bed held evenly moist, offer no fertilizer, and cut the stand as its first pale flowers open, ahead of ripe seed.
Light
Buckwheat does best in full sun and takes partial sun with little 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 has no drought tolerance and wilts fast in hot, dry stretches. It also hates wet feet and quits on waterlogged or heavy soils, so aim for moist but well drained.
Soil
It thrives on light to medium, well-drained loams and in fact prefers low-fertility ground, doing poorly on heavy, wet, or high-lime sites. A pH anywhere from 5.0 to 7.0 suits it, and it puts up with 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 is frost-tender, so one cold night kills it, and it sulks in extreme heat.
Humidity
Plain outdoor humidity is all it asks, so there is no number to chase. It cares far more for cool, moist soil than for the air around it.
Feeding
Leave the fertilizer be. Buckwheat is grown on low-fertility soils by design, and extra nitrogen only makes it flop over. It is no legume and fixes no nitrogen, but it does scavenge phosphorus and leave it more available for the next crop.
Pruning
When you grow 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 is 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 bears no cold at all. Direct sow it into warm soil from late spring through midsummer once all danger of frost has passed, watch the flowers open within 3 to 6 weeks, then either take it out at early bloom as a cover crop or harvest the grain at about 10 to 12 weeks, ahead of the first fall frost that 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 draws few real pests, so most trouble traces to timing and weather rather than disease. Read the signs below, line them up against what you see, and step in while it still does some good.
Buckwheat resurfaces as a weedy volunteer next season
Stray plants popping up in a later crop point to volunteer reseeding, which sets in when a stand flowers and lets its ripe seed fall before getting cut down. Timing is the answer. Take the stand out at early bloom, about 7 to 10 days after the first flowers open and well before any seed hardens, then scrape out the small heart-shaped seedlings while they are 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
Dark, collapsed leaves the morning after frost
Buckwheat is a frost-tender warm-season annual, so one cold or near-freezing night finishes it off and leaves the leaves and stems darkened and slumped. Nothing brings it back once frost lands on it, so let the kill mark the close of the crop and turn the soft residue under. Sow only once frost is behind you, and for grain, bring it in before the first fall frost arrives.
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
A sparse, scrappy stand usually means the ground was too harsh, since buckwheat is not drought tolerant and droops fast under midday sun, while it also gives up on heavy, waterlogged, or high-lime soil. Aim straight down the middle. Sow into light to medium, well-drained ground that keeps a steady bit of moisture, and skip both parched and soggy spots.
Fix:
- Sow into adequately moist, well-drained soil
- Avoid heavy, wet, or droughty sites
No nitrogen left behind for the next planting
Plenty of gardeners get tripped up here, yet buckwheat is a non-legume in the knotweed family and draws no nitrogen from the air, however green and full the stand looks. Put it to work on what it really delivers: quick weed cover, scavenged phosphorus, and a fast pile of green growth. For nitrogen, grow a legume cover crop with it or right behind it.
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 a prized honey and pollinator source, so for people the verdict reads good. The caution sits with 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 come down with 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 seldom bother with greens, but one that works through a good amount of the flowering plant can wind up queasy, and the fagopyrin it swallows may leave pale or thin-furred skin touchy in sunlight. Keep a nosy cat clear of cut bouquets and of standing plants in bloom.
Dogs Caution
A leaf or two snatched by a dog is rarely a problem, though a big mouthful of the green, flowering plant can churn its stomach. Keep an eye on pale-skinned or short-haired dogs for redness and itching on bare skin once they have spent time out under the sun.
Horses Moderate
Grazing horses face genuine risk, because heavy feeding on flowering buckwheat plus a stretch in the sun can set off fagopyrism. The white-marked, lighter stretches of the muzzle and legs blister, peel, and itch. Move affected horses into shade and off the plant.
Rabbits Moderate
Rabbits should not graze much of the green plant. The fagopyrin held in the leaves and flowers can make light skin and thin-furred spots, the ears above all, flare up in sunlight with sore, sunburn-like patches.
Livestock Moderate
Cattle, sheep, goats, and pigs are the usual sufferers of fagopyrism. After grazing a lot of flowering buckwheat and standing out in the sun, their light-colored or exposed skin swells, blisters, and itches. Keep them off heavy stands while in bloom.
Birds Caution
Birds tuck into the cleaned grain with no harm done, since the seed holds no fagopyrin. The green plant is the concern. Heavy feeding on the flowering tops could leave bare or pale-skinned birds touchy in the sun, so the worry rides with the foliage, not the seed.
People Grain safe
The hulled grain and buckwheat flour make a wholesome, gluten-free food that is safe to eat. The lone caveat is the raw green plant: handling or eating a large quantity of the flowering tops has, in rare cases, left light skin touchy in sunlight, so keep in mind 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 keep turning up, whether you are after grain, flour, or a fast cover crop. These are the ones worth knowing by name.
Common buckwheat (Fagopyrum esculentum)
This is the buckwheat in nearly every grower's hands, a fast warm-season broadleaf carrying white to pinkish flowers, with named cultivars such as Mancan and Manor that do double duty for grain and cover.
Tartary buckwheat (Fagopyrum tataricum)
A tougher relative bearing small greenish self-pollinating flowers, this species takes cold in stride and holds more rutin, though its grain carries a noticeably more bitter taste.
Silverhull
An old common-buckwheat type valued for milling, Silverhull bears silvery-gray, thin-hulled seed that grinds into flour with little effort.
How to propagate
Buckwheat could not be plainer 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 grown from seed straight in the ground almost without exception. Drop it into warm soil once all danger of frost has passed, anywhere from late spring through midsummer, and the seedlings push up in just 3 to 5 days. From there the stand sprints to cover the soil within a few weeks, which is what makes it such a good weed smotherer.
Myths
Buckwheat is a wheat, a grain grass full of gluten.
The name throws people off. Buckwheat is a broadleaf pseudocereal in the knotweed and smartweed family, with no tie to true wheat and nothing shared with cereal grasses. It is naturally gluten-free, which is why its flour works for anyone who cannot eat wheat.