Agrostis capillaris (colonial bentgrass)

Agrostis, Genus, capillaris, Species,

Genus & species

colonial bentgrass

Poaceae

Europe (British Isles, Scandinavia, temperate continental Europe); naturalized in cool-temperate regions worldwide

SunFull Sun

WaterModerate to high

HardinessZones 3a–7b

Overview

Agrostis capillaris is a cool-season perennial turf grass forming dense low-growing mats through both short rhizomes and tillers. Leaf blades are narrow — typically 2–4 mm (0.08–0.16 inch) wide — with a smooth surface and a boat-shaped leaf tip characteristic of the genus. Delicate open panicles of tiny spikelets emerge on slender culms 8–20 inches (20–50 cm) tall and carry a hazy purplish-green to tan inflorescence when in flower. The species carries both short rhizomes and above-ground stolons, though the rhizomes are less developed than in Agrostis stolonifera, and the growth habit is more upright than creeping bentgrass. Moderate foot traffic is tolerated once turf is established; heavy traffic during hot weather causes stress damage. The species is not drought-tolerant; consistent summer moisture is required to maintain turf density, and performance drops quickly in hot dry conditions. Hardy in USDA zones 3–7.

Native Range

Agrostis capillaris is native to Europe, particularly throughout the British Isles, Scandinavia, and the temperate regions of continental Europe, in grasslands, meadows, heathlands, and roadsides. The species has naturalized widely in cool-temperate regions of North America and elsewhere and appears as a weedy grass in lawns and pasture.

Suggested Uses

Planted on golf course fairways and tees, residential and commercial lawns where a low-mowing cool-season turf is wanted, as an overseed for winter color in cool-season turf, in naturalized meadow plantings, and for erosion control on slopes in USDA zones 3–7. The species fits positions where consistent summer moisture can be supplied, and is not used in hot summer climates or dry-site applications where Festuca ovina or Bouteloua gracilis perform better. The open flowering panicle contributes a hazy texture in naturalized plantings where the grass is allowed to flower.

How to Identify

Identified by a low-growing cool-season perennial grass 2–4 inches (5–10 cm) tall when mowed, with narrow 2–4 mm (0.08–0.16 inch) wide leaf blades carrying a boat-shaped tip and smooth surface, and open delicate flowering panicles with a hazy purplish-green to tan appearance on 8–20 inch (20–50 cm) culms in late spring to early summer. Separated from Agrostis stolonifera (creeping bentgrass) by the more upright growth habit and the shorter less-prominent rhizomes (creeping bentgrass spreads aggressively by long above-ground stolons). Boat-shaped leaf tips place the grass in Agrostis.

Appearance

Bloom Information

Flowers in late spring to early summer, producing open panicles of tiny spikelets in a hazy purplish-green to tan cloud on slender culms 8–20 inches (20–50 cm) tall. In turf applications, regular mowing prevents flowering; in naturalized plantings, inflorescences are left to mature for the cloud-like effect through June and July.

Detailed Descriptions

Flower Description

Purplish-green to tan; tiny spikelets in open delicate panicles on slender culms 8–20 inches (20–50 cm) tall

Foliage Description

Medium to dark green; narrow 2–4 mm (0.08–0.16 inch) wide; smooth surface; boat-shaped leaf tip

Growing Conditions

Sun Requirements

Full Sun

Soil pH

5.5-7.0

Water & Climate

Water Needs

Moderate to high

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Plant in full sun to partial shade in moist acidic to neutral soil at pH 5.5–7.0. The species requires consistent moisture and performs poorly under drought; regular watering during establishment and through summer dry spells maintains turf density. Balanced fertilizer in early spring and early fall supports vigorous growth. Overseeding of thin areas and renovation every few years maintains performance in high-traffic turf. Heavy foot traffic during hot weather should be limited because heat-stressed plants recover slowly. Hardy in USDA zones 3–7.

Pruning

Mow regularly at 0.5–1.5 inches (1.3–3.8 cm) for turf applications; frequent light mowing supports dense growth and prevents seed-head formation. For naturalized plantings, flowers and seeds are allowed to mature before the annual cutback in late summer. Remove thatch buildup annually through light dethatching in spring or fall.

Toxicity

Non-toxic

Related Agrostis species

Grass