Ornamental · Poaceae
Oats
Avena sativa
A fast, easygoing cool-season grass, and honestly a bit of an overachiever: it can be a feed grain, a windowsill's cat grass, or a cover crop out in the field.
Full sun
Every 3–7 days
60–120 days
USDA 2–9
Overview
Oats are about as easy as a grass gets, and that's a big reason they turn up in so many jobs. The very same plant, Avena sativa, ends up as a cover crop, livestock forage, the grain in your breakfast bowl, and the cat grass sold for pets to nibble. All that really changes is how you sow it and look after it.
It's a cool-season annual, so it does its best work in cool, moist weather and pretty much sulks through heat and drought. It comes up fast, throws down quick weed-smothering cover, and grabs loose nutrients before rain can wash them away. Want to give a slow legume a leg up? Plenty of growers pair oats with peas or clover, where the oats play nurse crop, shelter the seedlings, then die back and hand over the bed.
Where winters get cold enough, oats die off on their own and save you the whole job of killing the stand. Where they don't, the plant rides out winter and sets seed, so you mow or till before it heads out. Figuring out which side of that line you garden on is the single handiest thing to sort out before you sow.
Care
The short version: oats are happiest in full sun with cool, moist soil, and they need little or no extra feeding. Just sow the seed straight into the ground, keep it from drying out, and watch out for warm winters that let the stand reseed.
Light
Oats want full sun and crop best right out in the open. They'll put up with a bit of partial shade, but any more than that and the stand thins out and gets weak.
Water
Being a cool-season grass, oats like it cool and moist and don't handle heat or drought all that well. So keep the soil from drying out, since dry spells stress the plant and cut into both the cover and the yield.
Soil
Not many cereals are this adaptable. Oats like a well-drained loam best, but they'll 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'll germinate in chilly soil and does its best work before the summer heat really kicks in.
Humidity
Plain outdoor humidity is all oats ask for, so there's no number to chase. What helps more is good airflow, since crowded, damp stands are what invite the rusts and other leaf diseases.
Feeding
Oats want next to nothing, 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, though, because too much makes soft growth that flops over.
Pruning
There's really no pruning to bother with. In mild-winter regions, mow or till the stand before it sets seed to head off weedy volunteers, while in cold climates the plant winterkills on its own 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 just 6 to 12 inches (15 to 30 cm) across. Sow it thick, since oats grow as a close stand rather than getting spaced out like a garden vegetable.
When to plant
Oats run on cool weather and a frost clock, plain and simple. 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. It heads up in spring to summer, and the grain's 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 really don't give you much grief, especially as a short-term cover crop. And when something does come up, it tends to show across the whole stand rather than on one plant. Match what you're seeing to the notes below and step in before it spreads.
Grazing cattle, sheep, or goats get sick on stressed forage
Here's the thing, the plant itself isn't poisonous. When oats get hit by drought, frost, or a heavy dose of nitrogen, the forage can build up nitrate, and it's that nitrate that troubles grazing ruminants like cattle, sheep, and goats. So test stressed or heavily fed forage before you graze it, steer clear of drought- or frost-stressed stands, and keep in mind that ensiling brings nitrate down. The standing plant and the grain? Totally fine 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 make it through winter and reseed instead of dying off
So what happened here? A mild winter never handed the stand the hard cold it needs to die off, so it just greened back up, headed out, and dropped seed for next year. Oats really only winterkill in Zone 6 and colder and across a good chunk of Zone 7. Anywhere warmer, you can't lean on the frost, so plan to mow or till before the plants set seed.
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
Orange rusty spots, dark powdery blotches, or yellowed weak leaves
These are just the usual cereal bugs. Crown and stem rust show up as orange-brown pustules, smut leaves dark powdery masses, and barley yellow dwarf virus, which aphids carry, yellows and reddens the leaves while it stunts the plant. So rotate away from other cereals, start with clean or resistant seed, and keep the aphids in check. Grown as a quick cover crop, though? Oats hardly ever take enough of a hit to worry about.
Fix:
- Rotate away from cereals
- Use clean, treated, or resistant seed where available
- Control aphids that vector barley yellow dwarf
Tall stems keel over and spread flat across the soil
That flopped-over look is lodging, and it usually just means the ground was a little too rich or got a bit too much nitrogen, which pushes soft, top-heavy growth that a hard rain or gust can lay right over. So ease up on the extra nitrogen when you're growing oats as a cover or nurse crop. And if you're not after grain? Lodged oats are honestly no loss, since they still smother weeds and make a nice mulch.
Fix:
- Avoid extra nitrogen fertilizer when grown as a cover or nurse crop
- Mow tall growth before it lodges if managing biomass
Toxicity
Honestly, 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 catch? For grazing ruminants, drought- or frost-stressed forage can carry nitrate that's worth testing for.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
This is the classic cat grass, grown on purpose for cats to nibble. A little chewing won't hurt, and it might even help your cat cough up a hairball.
Dogs Safe
Dogs can graze the blades no problem, and that same pet grass sold for cats works just fine for them too. Plain oats and oat grass? Not on any toxic-plant list.
Horses Safe
Oats have been a go-to feed grain for horses forever, and they can graze the grass without a worry. There's nothing in the plant that'll poison them.
Rabbits Safe
Rabbits do great on oat hay and fresh oat grass, and both are a normal part of what they eat.
Livestock Safe
The plant itself is good, non-toxic forage. The one thing to keep an eye on is nitrate, which can build up in oats stressed by drought, frost, or heavy nitrogen, so test any iffy forage before you turn ruminants out on it.
Birds Safe
Oats are a common bird feed, and chickens and wild birds happily eat the grain and peck at the grass.
People Safe
The grain is a staple you'll know well, eaten as oatmeal, oat flour, and plenty more. This 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 handful of types, sorted by season and what they're grown for. Here are the ones worth telling apart.
Spring oats
The most common kind you'll run into, sown in spring or late summer, heading up without any cold spell and winterkilling once hard frost shows up.
Winter oats
The hardier types for mild-winter regions, where they ride out the cold and head up the next spring.
Forage / hay oat varieties
These are bred for lots of leafy growth, like ForagePlus, and they're cut for hay, silage, or grazing instead of grain.
Hull-less (naked) oats
These thresh clean out of the hull to leave a bare groat, and folks value them 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 grow from seed and nothing else, and you sow it right where it's 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 only grow from seed, and you just sow it right 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, and tuck the seed half an inch to an inch deep. It'll sprout even in cool soil down to about 38°F (3°C) and give you usable cover in 6 to 10 weeks, which is exactly why it's such a quick, cheap, reliable crop to get going.
Myths
Cover-crop oats are their own thing, nothing like the food oats or the cat grass sold for cats to chew.
Nope, they're all the same thing. Cover-crop oats, forage and hay oats, grain oats, and the grass grown for cats to nibble are all the same plant, Avena sativa. What changes is just how you sow it and manage it.
Oats will always winterkill by themselves, so there's never a need to knock down the stand yourself.
Would be handy if that were always true, but oats only die off on their own where winters get cold enough, roughly Zone 6 and colder and much of Zone 7, down into the low 20s degrees F. Where it's milder, they live right through winter and set seed, so you'll have to mow or till the stand before it heads out.