Ornamental · Poaceae
Annual Ryegrass
Lolium multiflorum
Sow it in fall and annual ryegrass rewards you with fast cover, hungry roots, and a stand that mostly steps aside by spring.
Full sun
Every 3–7 days
50–120 days
USDA 6–9
Overview
If you need bare ground covered in a hurry, annual ryegrass is a kind place to start. It is a cool-season bunchgrass in the genus Lolium, with bright, glossy leaves, and it comes up and roots faster than nearly anything else you can sow, so early wins come easily. Gardeners and farmers lean on it to hold soil through winter, mop up leftover nitrogen, and feed grazing animals.
Just don't mix it up with cereal rye or with its perennial cousin. This one is a true annual that lives its whole life in a single season, sending up flower spikes in spring and dying back when heat or cold arrives. That short life is a gift, because a cover crop that finishes on its own spares you a termination pass.
The one thing to watch is how freely it spreads. Annual ryegrass sets seed heavily and can be stubborn to see off, so it can slip into fields and edges as a weedy volunteer if a stand is left to mature. Stay on top of the timing and it works alongside you, and that part is well within reach.
Care
The short version: sow it shallow into moist soil in full sun, keep it watered while it settles in, and it manages most soils on its own. Mow no closer than 3 to 4 inches, and end it at early bloom before it seeds.
Light
Annual ryegrass is happiest in full sun yet takes partial shade without complaint. More light gives you a thicker, faster stand, which is just what you hope for from a cover crop racing to blanket bare ground.
Water
It asks for steady soil moisture to come up fast and settle in, and it sulks when left dry. A long stretch of heat and drought will finish it off, though it copes with wet and even briefly flooded soil better than most cover crops, so a soggy patch is rarely cause for worry.
Soil
Few grasses are this easygoing about where they grow. It takes clay, loam, sand, rocky, and high-organic soils across a generous pH of 5.0 to 7.5, and it does best of all in rich, moist, well-drained loam.
Temperature
This is a cold-tolerant grass that holds up from about 10°F to 81°F (-12°C to 27°C). It loves cool weather and eases off once summer heat arrives, which is exactly why it is sown for fall and spring.
Humidity
Outdoor humidity simply is not something to fuss over, so there is no figure you need to hit. What matters far more is moisture in the soil, the thing that powers its quick germination and early growth.
Feeding
Most of the time it wants no feeding at all, since it gathers leftover soil nitrogen rather than relying on fertilizer. Add a nitrogen source at planting only where the soil is genuinely poor.
Pruning
Mow to hold it as living mulch or temporary turf, but never closer than 3 to 4 inches. When you are finished with it, terminate at early bloom by mowing, tilling, or a contact herbicide, since mowing on its own may not see off an established stand.
Repotting
none
Size & spacing
Grown as a stand rather than as spaced plants, it reaches 1 to 3 feet (30 to 91 cm) tall, with each plant filling only about 8 to 12 inches (20 to 30 cm). The seeding rate, not spacing, decides the density you end up with.
When to plant
Because annual ryegrass is a cool-season grass, it suits the milder shoulders of the year rather than the heat of summer, and that makes it forgiving to time. Direct sow it from late summer into fall to overwinter in mild zones, or in early spring, and in cold country get it down at least 40 days before the first killing frost. Flower spikes arrive in spring, and that is your gentle reminder to terminate before seed sets.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: not typically started indoors; direct sown
- Plant: Late summer to early fall (late July through October) for overwintering in mild zones, or early spring; in zone 5 and colder sow at least 40 days before first killing frost
- Harvest: Flower spikes in spring; terminate before seed set. As a cover crop, biomass is produced over fall, winter and spring.
Hardiness
USDA hardiness zones: 6–9
Temperature: down to -23°C
Troubleshooting
Trouble with annual ryegrass has less to do with disease and more to do with timing and control, which is reassuring since both are in your hands. The main risks are letting it seed, losing a stand to winter or drought, and a thin start from dry ground. Find what matches what you are seeing below and act early, before a small problem carries into the next crop.
It returns on its own as an unwanted volunteer
If a stand is allowed to flower and finish setting seed, next season can hand you a few surprises, and that is worth heading off gently. A single plant drops about 300 seeds that sprout readily, and a mower on its own rarely settles the matter, partly because certain populations brush off glyphosate. The good news is the fix is simple: end the stand at early bloom with a disk, a plow, or a contact herbicide before any seedheads ripen.
Fix:
- Terminate at early bloom before seed set by disking, plowing, or a non-persistent contact herbicide
- Use a chaff/seed collection system at harvest if grown to seed nearby
- Repeat control passes since seeds germinate in both fall and spring across a wide temperature range (36 to 104 degrees F)
Bare brown patches open up through the winter
Take heart, because this is usually just winterkill, and it shows up most in zone 5 and colder where no snow sits over the crowns to keep them cozy. Summer heat and drought above roughly 80°F (27°C) can thin a planting the same way. Sow early enough for the roots to settle in before the cold, at least 40 days ahead of the first killing frost, and where you actually wanted a cover that bows out on its own, treat the dieback as a welcome bonus.
Fix:
- Reseed bare areas in mild zones, or accept winterkill where a self-terminating cover is desired
- Plant early enough (at least 40 days before first killing frost) so plants establish before cold
Thin, spotty emergence after you sow
Most often this comes down to dry soil, since the seed leans on steady moisture to come up fast, and anything buried too deep struggles to push to daylight. The remedy is forgiving: sow shallow at 1/4 to 1/2 inch deep, and water gently if the rain stays away. Hold to a sensible rate as well, around 10 to 20 lb per acre drilled or 20 to 30 lb broadcast, and those thin spots knit together before long.
Fix:
- Sow at 1/4 to 1/2 inch depth and ensure rainfall or irrigation for good establishment
- Use proper seeding rates (10-20 lb/acre drilled, 20-30 lb/acre broadcast)
Toxicity
As a lawn or cover crop, annual ryegrass is safe around cats and dogs, who at worst get a mild upset stomach from chewing a little grass. The real caution is for horses and grazing livestock: ryegrass carrying fungal endophytes holds alkaloids that bring on ryegrass staggers, a tremor and incoordination syndrome. Graze or cut it before the seedheads form and you stay on the safe side.
Toxic to
Horses · Rabbits · Livestock · Birds · People
Safe for
Cats · Dogs
Horses Moderate
Here is where care is warranted: a horse grazing endophyte-infected ryegrass can come down with ryegrass staggers, showing muscle tremors, a stiff or jerky way of moving, and stumbling that worsens the instant the animal is stressed or pushed forward. Ergot alkaloids in the seedheads also tighten the blood vessels.
Rabbits Caution
Plain ryegrass is everyday forage, yet the same fungal alkaloids that trouble grazing livestock can gather in older, seedy growth. Keep your rabbits clear of heading or endophyte-affected stands and offer young, clean grass instead.
Livestock Moderate
Cattle, sheep, and goats on affected pasture can take on the same staggers from lolitrem B, trembling and going down when they grow excited or try to run. The ergovaline beside it narrows the blood vessels and drags on their condition.
Birds Caution
Ryegrass seed shows up across many bird diets and is no recognized poison. The open question is ergot in mature seedheads, so it pays to keep birds from gorging on heavy, fungus-marked grain.
People Caution
No part of this grass is meant for the plate, so there is simply nothing to gather and cook. For people the genuine bother is the pollen, a familiar trigger of hay fever come late spring.
Cats None
You can relax here, because the grass holds no toxin and the ASPCA leaves it off its list of dangers. A curious cat that chews a blade or two might cough a bit back up, and that really is as far as it goes.
Dogs None
It is perfectly fine to have your dog padding across it as a lawn or cover crop. A mouthful of the foliage brings nothing more than the brief, mild tummy upset that any grass might.
Safe as a lawn, forage, or cover-crop grass around pets; the foliage itself is non-toxic to cats and dogs. For pastured horses and livestock, manage endophyte- and ergot-affected seedheads - cut or graze before heading and avoid feeding affected, mature ryegrass.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
A handful of distinct types go by the ryegrass name, and they don't all behave alike. These are the ones worth learning to tell apart before you reach for seed.
Annual / Italian ryegrass (Lolium multiflorum)
This is the quick cover-crop and forage type, a short-lived cool-season bunchgrass with bright, glossy leaves that usually dies back in the cold of harsh zones.
Perennial ryegrass (Lolium perenne)
A close cousin raised for turf and pasture that returns each year, unlike the annual Lolium multiflorum that fades away every season.
Westerwolds annual ryegrass
A true-annual form of Lolium multiflorum that blooms and sets seed in its very first season with no need for a cold spell, valued for fast, single-season cover or forage.
Diploid vs tetraploid types
Tetraploid cultivars hold doubled chromosomes that lend them larger, juicier leaves and seeds along with sweeter palatability, while diploids settle into denser, finer stands.
How to propagate
Annual ryegrass is grown just one way, from seed sown straight into the ground, and it really could not be much gentler on a first-timer.
SeedEasy
Late summer to early fall for overwintering, or early spring; sow at least 40 days before first killing frost in cold zones · Germinates and establishes very quickly, often within 1-2 weeks in moist cool soil
There is nothing tricky here: annual ryegrass starts from seed sown right into the ground, never indoors. Put it down in late summer to early fall if you would like it to overwinter, or in early spring, and in cold zones get the seed in at least 40 days before the first killing frost. Broadcast at 20 to 30 lb per acre or drill at 10 to 20 lb per acre, only 1/4 to 1/2 inch deep, into moist soil, and you will see it sprout and take hold within a week or two.
Myths
Annual ryegrass is the same plant as cereal rye.
These two share part of a name and little besides. Annual ryegrass is Lolium multiflorum, a fine-leaved forage and turf bunchgrass, while cereal rye is Secale cereale, the tall, very cold-hardy grain that ends up in bread. Two separate grasses from two separate genera, so the seed and the growing advice for one will not carry over to the other.