Ornamental · Poaceae
Oats
Avena sativa
A fast, forgiving cool-season grass that doubles as a cover crop, a feed grain, and the cat grass on your windowsill.
Full sun
Every 3–7 days
60–120 days
USDA 2–9
Overview
Oats are one of the easiest grasses you can grow, which is part of why they turn up in so many roles. The same plant, Avena sativa, becomes a cover crop, livestock forage, the grain in your breakfast bowl, and the cat grass sold for pets to nibble. How you sow and manage it is all that changes.
This is a cool-season annual that does its best work in cool, moist weather and sulks in heat and drought. It comes up fast, throws down quick weed-smothering cover, and pulls up loose nutrients before they wash away. Growers often pair it with a slow legume like peas or clover, where the oats act as a nurse crop that shelters the seedlings and then dies back to hand the bed over.
Where winters get cold enough, oats die on their own and save you the trouble of killing the stand. Where they don't, the plant overwinters and sets seed, so you mow or till before it heads out. Knowing which side of that line you garden on is the single most useful thing to settle before you sow.
Care
The short version: full sun and cool, moist soil suit oats best, with little or no extra feeding. Sow the seed straight into the ground, keep it from drying out, and watch for warm winters that let the stand reseed.
Light
Oats want full sun and crop best out in the open. They'll put up with a bit of partial shade, but more than that thins the stand and weakens it.
Water
Being a cool-season grass, oats like things cool and moist and don't handle heat or drought well. Keep the soil from drying out, since dry spells stress the plant and cut both cover and yield.
Soil
Few cereals are this adaptable. Oats favor a well-drained loam but take poor, somewhat acidic, and even wet ground better than most grains, handling a pH anywhere from 4.5 to 8.0.
Temperature
This is a tough, cool-weather plant that grows across a wide range, from about 21°F to 84°F (-6°C to 29°C). It germinates in chilly soil and does its best work before summer heat sets in.
Humidity
Plain outdoor humidity is all oats need, so there's no figure to hit. Good airflow does more good here, since crowded, damp stands invite the rusts and other leaf diseases.
Feeding
Oats ask for very little, and as a cover or nurse crop they often need no fertilizer at all, especially in a fall or legume-mix sowing. Go easy on the nitrogen, because too much makes lush growth that flops over.
Pruning
There's no pruning to speak of. In mild-winter regions, mow or till the stand before it sets seed to stop weedy volunteers, while in cold climates the plant winterkills and needs nothing.
Repotting
none
Size & spacing
A stand runs about 2 to 4 feet (60 to 122 cm) tall, with each plant taking up only 6 to 12 inches (15 to 30 cm) across. Sow it thick, since oats are grown as a close stand rather than spaced like a garden vegetable.
When to plant
Oats run on cool weather and a frost clock. Sow in late summer to early fall, about 40 to 60 days before your first killing frost so the cold can take the stand down, or sow again in early spring. The plant heads up in spring to summer, with grain ready to harvest by mid to late summer.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Not typical; direct sown outdoors
- Plant: Late summer to early fall (40 to 60 days before first killing frost, to winterkill) or early spring
- Harvest: Open drooping branched panicle of spikelets in spring to summer; grain harvest mid to late summer
Hardiness
USDA hardiness zones: 2–9
Temperature: down to -46°C
Troubleshooting
Oats give you little trouble, especially grown as a short-term cover crop. The few problems that come up tend to show in the stand as a whole rather than on one plant. Match what you see below and step in before it spreads.
Grazing cattle, sheep, or goats sicken on stressed forage
This isn't the plant being poisonous. Oats hit by drought, frost, or heavy nitrogen can build up nitrate in the forage, and that nitrate is what troubles grazing ruminants like cattle, sheep, and goats. Test stressed or heavily fed forage before grazing it, skip drought- or frost-stressed stands, and note that ensiling brings nitrate down. The standing plant and the grain stay safe for pets and people.
Fix:
- Test stressed or heavily fertilized forage for nitrate before grazing or feeding
- Ensiling can reduce nitrate levels
- Avoid grazing drought- or frost-stressed stands
Oats survive the winter and reseed instead of dying back
When a winter stays mild, the stand never gets the hard cold it needs to die off, so it greens up, heads out, and drops seed for next year. Oats winterkill reliably only in Zone 6 and colder and across much of Zone 7. Anywhere warmer, plan to mow or till before the plants set seed rather than counting on the frost to do it.
Fix:
- Mow or till the stand before seed set
- Terminate by herbicide or mowing soon after the vegetative stage
- Do not rely on winterkill termination in mild-winter areas
Rusty pustules, dark powder, or yellow stunted leaves
These are the usual cereal diseases. Crown and stem rust show as orange-brown pustules, smut leaves dark powdery masses, and barley yellow dwarf virus, carried by aphids, turns leaves yellow and red while stunting the plant. Rotate away from other cereals, start with clean or resistant seed, and keep aphids in check. As a short-term cover crop, oats rarely suffer enough to matter.
Fix:
- Rotate away from cereals
- Use clean, treated, or resistant seed where available
- Control aphids that vector barley yellow dwarf
Tall stems flop over and lie flat on the ground
This is lodging, and it usually means the soil is too rich or got too much nitrogen, which pushes lush, top-heavy growth that a hard rain or a gust of wind then knocks over. Hold back on extra nitrogen when you grow oats as a cover or nurse crop. If you aren't after grain, lodged oats are no real loss and even smother weeds and form a useful mulch.
Fix:
- Avoid extra nitrogen fertilizer when grown as a cover or nurse crop
- Mow tall growth before it lodges if managing biomass
Toxicity
Oats are about as safe as a plant gets. The grain feeds people and animals alike, and the grass is grown on purpose as cat grass for pets to nibble, so nothing here is poisonous to cats, dogs, horses, rabbits, birds, livestock, or children. The one caveat is for grazing ruminants, since drought- or frost-stressed forage can carry nitrate that is worth testing for.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
Oat grass is the classic cat grass, grown on purpose for cats to nibble. A little chewing is harmless and may even help a cat clear hairballs.
Dogs Safe
Dogs can graze the blades without harm, and the same pet grass sold for cats works for them too. Plain oats and oat grass aren't on any toxic-plant list.
Horses Safe
Oats are a long-standing feed grain for horses and the grass is fine to graze. Nothing in the plant is poisonous to them.
Rabbits Safe
Rabbits do well on oat hay and fresh oat grass, both a normal part of their diet.
Livestock Safe
The plant itself is wholesome forage and is not toxic. The one thing to watch is nitrate, which can build up in oats stressed by drought, frost, or heavy nitrogen, so test questionable forage before turning ruminants out on it.
Birds Safe
Oats are a common bird feed, and chickens and wild birds eat the grain and pick at the grass freely.
People Safe
The grain is a staple food, eaten as oatmeal, oat flour, and more. The plant is grown for people to eat.
Like other cereal grasses, drought- or frost-stressed oat forage can accumulate nitrates that may harm grazing ruminant livestock, but the plant is not poisonous to pets or people.
Varieties
Oats come in a few types sorted by season and end use. These are the ones worth knowing apart.
Spring oats
The most common kind, sown in spring or late summer, heading without any cold spell and winterkilling once hard frost arrives.
Winter oats
Hardier types for mild-winter regions, where they live through the cold and head the following spring.
Forage / hay oat varieties
Bred for heavy leafy growth, like ForagePlus, and cut for hay, silage, or grazing rather than grain.
Hull-less (naked) oats
Thresh clean of the hull to leave a bare groat, prized for both feed and food.
Companions
Oats earn their keep beside slow-starting legumes, where they nurse the young plants along and then bow out as the season turns.
Plant near
Field peas: Oats serve as a nurse crop, providing quick weed-suppressing cover and support while the slower legume establishes.
Clover: Oats nurse establishing clover, suppressing weeds and scavenging nutrients while winterkilling to release the legume.
Hairy vetch: Oats added to slow-establishing vetch improve legume survival and provide cover that winterkills in many areas.
How to propagate
Oats are grown from seed and nothing else, sown right where they are meant to grow.
SeedEasy
Late summer to early fall or early spring · Germinates quickly (germinates at about 38 degrees F); usable cover in 6 to 10 weeks
Oats grow only from seed, sown directly outdoors in late summer to early fall or in early spring. Drill it at about 60 to 75 pounds an acre, or broadcast 80 to 100 pounds an acre, setting the seed half an inch to an inch deep. It sprouts in cool soil down to about 38°F (3°C) and makes usable cover in 6 to 10 weeks, which is what makes it such a quick, cheap, dependable crop to start.
Myths
Cover-crop oats are a different plant from food oats and the oat grass sold as cat grass.
Cover-crop oats, forage and hay oats, grain oats, and the grass grown for cats to nibble are all the same plant, Avena sativa. The only difference is how you sow and manage them.
Oats always winterkill and end themselves, so you never have to kill the stand.
Oats die off on their own only where winters turn cold enough, roughly Zone 6 and colder and much of Zone 7, down into the low 20s degrees F. In milder regions they live through the winter and set seed, so you have to mow or till the stand before it heads out.