Is this grass invasive?

Yes, it can spread aggressively in certain environments and is considered a weed in many regions.

Does it need full sun?

It prefers full sun but will tolerate partial shade.

Plant guide

Tall oatgrass.

Arrhenatherum elatius

Pronounced uh-ren-uh-THEE-rum ee-LAY-tee-us

Also known as Bulbous Oatgrass, False Oat Grass, False Oat-Grass, Onion Couch, Onion Twitch, Onion-root Twitch, Ray-grass-de-france, Tall Oat Grass

Tall oatgrass is a hardy, perennial bunchgrass that thrives in meadows and pastures. It is quite adaptable and often grows in clumps that can reach impressive heights. You will find it is a common sight in temperate regions across the globe.

At a glance

Care level: Easy
Plant type: Perennial grass
Light: Full sun
Indoor light: Direct sun
Water: Every 7 to 14 days
Mature size: 1.5 meters
Growth rate: Fast
Hardiness: USDA 4 to 9
Bloom time: Late spring to early summer

Care

This grass is very low maintenance and prefers open, sunny spots. Watch for excessive spread if you are planting it in a garden setting. Ensure the soil remains well drained to keep the roots happy.

Watering: Water deeply during dry spells to maintain steady growth.
Feeding: A light application of balanced fertilizer in early spring is plenty.
Pruning: Cut back the foliage to the ground in late winter to encourage fresh growth.
Repotting: Divide the clumps every few years to keep the plant vigorous.
Soil: Well drained loam
Soil pH: 6.0 to 7.5
Temperature: -34 to 35°C
Humidity: 40 to 70%

Safety

People: There are no significant reports of human toxicity.
Children: The sharp leaf edges can cause small cuts if handled roughly by children.
Contact allergens: The leaf blades have fine, sharp edges that can cause minor skin irritation.
Airborne allergens: The pollen is a common allergen for those sensitive to grass pollen during the flowering season.
Edibility: This grass is not intended for human consumption.

How to identify it

Tall, tufted perennial grass
Flat, rough textured leaves
Loose, nodding panicle inflorescence
Spikelets with bent awns

Height: 0.6 to 1.5m
Spread: 0.3 to 0.6m
Leaves: green, blue-green, deciduous
Flowers: green, yellow, purple, 15 to 30cm

Problems to watch for

RustCommon
DehydrationUncommon
ErgotUncommon
SmutUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: division, seed
When to plant: spring, autumn

Pair with sturdy perennials that can compete with its vigorous growth habit.

Grows well with

Coneflower · They share similar sun and soil requirements.
Black Eyed Susan · The contrasting textures look great in a meadow planting.

Similar species

Oat Grass · They share a similar appearance in their flowering structures.

Science

Family: Poaceae
Genus: Arrhenatherum
Order: Poales
Class: Liliopsida
Native range: Europe and parts of Western Asia.
Conservation: This species is considered invasive in many parts of North America and should be planted with caution.

It thrives in well drained soils and often colonizes disturbed ground.

Value to wildlife: larval host plant, nesting material
Pollinators: bees, butterflies
Uses: ornamental grass, erosion control, meadow planting

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 7/9
Temperature: 5/9
Moisture: 5/9
Nutrients: 5/9

Taxonomy resolved against GBIF.

Questions people ask

Is this grass invasive?: Yes, it can spread aggressively in certain environments and is considered a weed in many regions.
Does it need full sun?: It prefers full sun but will tolerate partial shade.

Where the name comes from

The genus name Arrhenatherum comes from the Greek words for male and awn, referring to the awned male flowers. The species name elatius means taller.

Good to know

It is commonly known as tall oat grass.
The species name elatius refers to its tall growth habit.
It is often found growing in meadows and along roadsides.

Keep your tall oatgrass growing

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.