Ornamental · Polygonaceae
Buckwheat
Fagopyrum esculentum
Drop it into warm soil and buckwheat covers the ground, smothers weeds, and feeds the bees in just a few weeks.
Full sun
Every 5–10 days
70–90 days
USDA 3–10
Overview
Buckwheat is one of the fastest things you can get into the ground. The name throws people off, since it has nothing to do with wheat and isn't even a grass. It's really a broadleaf pseudocereal in the knotweed family, grown both for its little triangular grain and as a quick summer cover crop. A few weeks after you sow it, it spreads a carpet of heart-shaped leaves and a soft haze of small white to pinkish flowers across bare ground.
Where it shines is buying you time and tidying up the soil. A stand of it smothers weeds before they can get going, digs up phosphorus and hands it off to whatever you plant next, and pulls in bees and other pollinators by the crowd. The catch? It can't fix nitrogen, since it isn't a legume, so when you need that, you'll want to team it up with a legume cover crop.
It barely asks for a thing and grows on poor, low-fertility ground that would leave choosier plants starving. The soft spot is its tender side. Buckwheat wilts in heat and dies at the first frost, so think of it as a warm-season filler between your main crops rather than something that sticks around all year.
Care
The short version: drop the seed straight into warm soil after frost, give it light, well-drained ground that stays evenly moist, leave the fertilizer alone, and cut it down at early bloom before it sets seed.
Light
Buckwheat is happiest in full sun and will take partial sun without complaint. The more light it gets, the faster it covers ground and the better it flowers, which is the whole point of growing it.
Water
Keep it on steady, even moisture, because buckwheat is not drought tolerant and wilts fast in hot, dry spells. It hates wet feet just as much, though, and flops on waterlogged or heavy soils, so you're shooting for moist but well drained.
Soil
It does best on light to medium, well-drained loams and actually likes low-fertility ground, while doing poorly on heavy, wet, or high-lime sites. A pH anywhere from 5.0 to 7.0 works for it, and it puts up with poor and slightly acidic soil better than most crops.
Temperature
Buckwheat is a warm-season annual that's comfortable from about 45°F to 95°F (7°C to 35°C). It's frost-tender, so one cold night ends it, and it gets cranky in extreme heat.
Humidity
Plain outdoor humidity is all it ever needs, so there's no number to chase. It cares way more about cool, moist soil than the air around it.
Feeding
Skip the fertilizer. Buckwheat gets grown on low-fertility soils on purpose, and a shot of extra nitrogen just makes it flop over. It isn't a legume and fixes no nitrogen, but it does dig up phosphorus and leave it handier for the next crop.
Pruning
Growing it as a cover crop? Mow or till at early bloom, roughly 7 to 10 days after those first flowers open. That ends the crop before viable seed forms and stops it from reseeding as a weed.
Repotting
none
Size & spacing
Plants get to 2 to 4 feet (60 to 120 cm) tall with a slim spread of 6 to 12 inches (15 to 30 cm). Since you sow it thickly as a stand rather than spacing it out, that narrow footprint is what lets it knit together and shade out the weeds.
When to plant
Buckwheat runs on warmth and has zero patience for cold. Sow it straight into warm soil from late spring through midsummer once all danger of frost has passed, watch the flowers open within 3 to 6 weeks, and then either cut it down at early bloom as a cover crop or pick the grain at about 10 to 12 weeks, before the first fall frost finishes it off.
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 hardly draws any real pests, so most of the trouble traces back to timing and weather rather than disease. Look over the signs below, match them to what's in front of you, and step in while it still does some good.
Buckwheat keeps popping up uninvited in your next plantings
What you're looking at is volunteer reseeding, and it shows up when a stand gets to flower and drop ripe seed before you've cut it back. So the cure is all about timing. Knock it down by mowing or tilling at early bloom, around 7 to 10 days after those first flowers open and before any seed turns hard, then run a hoe through the little heart-shaped seedlings while they're 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
Everything goes dark and droops after one cold night
Here's the thing: buckwheat is a frost-tender warm-season annual, so one cold or near-freezing night is all it takes to wipe it out and turn the leaves dark. Once frost has hit, there's no bringing it back, so just call it the natural end of the crop and work the leftovers into the ground. Wait to sow until frost's behind you, and if you're after grain, get it picked before that first fall frost shows up.
Fix:
- Accept frost kill as the natural end of the crop and incorporate residue
- For grain, harvest before the first frost
Patchy, struggling stand in hot or dry soil
Buckwheat is not drought tolerant and droops fast in midday heat, yet it also won't do well on heavy, soggy, or high-lime ground. So what you're after is the happy middle. Drop the seed into light to medium, well-drained soil that holds onto even moisture, and skip the spots that run too dry or stay too wet.
Fix:
- Sow into adequately moist, well-drained soil
- Avoid heavy, wet, or droughty sites
The next crop gets no nitrogen lift from it
Plenty of folks get tripped up here, but buckwheat is a non-legume in the knotweed family, and it just doesn't pull nitrogen out of the air, no matter how green and full it looks. Lean on what it really brings to the table: fast weed cover, phosphorus it digs up and shares, and a heap of quick green growth. Need nitrogen? Grow a legume cover crop right alongside it or straight after.
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
For people the verdict is good: the grain is a wholesome, gluten-free food and the flowers are a prized honey and pollinator source. The caution is the green plant. Its flowers and foliage hold a pigment called fagopyrin, and grazing animals that eat a lot 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 hardly ever go for greens, but one that puts away a fair bit of the flowering plant can end up queasy, and the fagopyrin that comes with it may leave light-colored or thin-furred skin touchy in the sun. Best to keep a nosy cat clear of cut bouquets and any plants standing in bloom.
Dogs Caution
A dog grabbing the odd leaf probably won't have any trouble, though wolfing down a lot of the green, flowering plant can bring on a stomach upset. Just keep half an eye on pale-skinned or short-haired dogs for redness and itching on bare skin once they've spent a while out in the sun.
Horses Moderate
Grazing horses face a genuine risk, because eating their fill of flowering buckwheat and then spending time in the sun can set off fagopyrism. The white-marked and lighter spots on the muzzle and legs blister, peel, and itch. Get affected horses out of the direct sun and away from the plant.
Rabbits Moderate
Don't let rabbits graze a lot of the green plant. The fagopyrin tucked in the foliage and flowers can make light skin and thin-furred spots, the ears most of all, react to sunlight with sore, sunburn-like patches.
Livestock Moderate
Cattle, sheep, goats, and pigs are the usual ones to come down with fagopyrism. When they graze heavily on flowering buckwheat and then stand around in the sun, their light-colored or bare skin swells, blisters, and itches. Keep them off thick stands that are in bloom.
Birds Caution
Birds tuck into the cleaned grain just fine and it does them no harm, since there's no fagopyrin in the seed. The thing to watch is the green plant. Feeding heavily on the flowering tops could leave bare or pale-skinned birds touchy in the sun, so the worry lands on the foliage, not the seed.
People Grain safe
The hulled grain and buckwheat flour make for a wholesome, gluten-free food that's safe to eat. The only real catch is the raw green plant: in rare cases, handling or eating a whole lot of the flowering tops has left light skin sensitive to sun, so keep in mind that 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 handful of buckwheat types keep turning up, whether you're after grain, flour, or a fast cover crop. These are the ones worth knowing by name.
Common buckwheat (Fagopyrum esculentum)
Odds are this is the buckwheat you've got, a quick warm-season broadleaf carrying white to pinkish flowers, with named cultivars such as Mancan and Manor that work for both grain and cover.
Tartary buckwheat (Fagopyrum tataricum)
Picture a tougher cousin: it puts out small greenish self-pollinating flowers, takes the cold in stride, and packs more rutin, though the grain tastes a good deal more bitter.
Silverhull
An old common-buckwheat favorite for milling, Silverhull has silvery-gray, thin-hulled seed that grinds into flour without much trouble.
How to propagate
Buckwheat couldn't be much easier to grow from seed, which is how 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 about as fuss-free as seed-grown plants get, which is how nearly everyone gets it going. Drop it right into warm soil once all danger of frost has passed, anytime from late spring through midsummer, and you'll see it break ground in just 3 to 5 days. After that it tears across the soil within a few weeks, and that's exactly why it smothers weeds so well.
Myths
Buckwheat is a kind of wheat or cereal grass and contains gluten.
Easy name to fall for, isn't it? Buckwheat is really a broadleaf pseudocereal in the knotweed and smartweed family, with no connection to true wheat and nothing shared with cereal grasses. It is naturally gluten-free, which is just why its flour works so well for folks who can't have wheat.