What hardiness zones is Agrostis gigantea suitable for?

Agrostis gigantea is suitable for USDA hardiness zones 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b.

What are the sun requirements for Agrostis gigantea?

Agrostis gigantea requires full sun to partial shade.

How much water does Agrostis gigantea need?

Agrostis gigantea has moderate water needs.

Wild Grasses

Agrostis gigantea

redtop

PoaceaeEurope

At a Glance

TypeGrass

Habitrhizomatous, spreading

Foliagedeciduous

Height12-24 inches

Widthspreads indefinitely

Growing Zones

USDA Hardiness Zones

3a - 8b

Zone 3a

Zone 3b

Zone 4a

Zone 4b

Zone 5a

Zone 5b

Zone 6a

Zone 6b

Zone 7a

Zone 7b

Zone 8a

Zone 8b

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Overview

Agrostis gigantea is a perennial cool-season grass known for its distinctive reddish-purple panicles and robust growth habit. This rhizomatous grass forms dense colonies through its spreading underground stems, creating thick stands that can persist for many years. The flat, linear leaves are typically 2-8 mm wide and can reach 12 inches in length, with a smooth texture and prominent parallel veining characteristic of the grass family. The most distinctive feature of Agrostis gigantea is its open, branched flower head (panicle) that emerges in summer, initially green but maturing to attractive reddish-purple hues that give the plant its common name. These delicate, cloud-like seed heads can reach 4-8 inches in length and create an attractive textural element in the landscape. The plant's ability to spread via rhizomes distinguishes it from other Agrostis species and contributes to its effectiveness as a turf grass and soil stabilizer.

Native Range

Agrostis gigantea is native to Europe and western Asia, where it naturally occurs in meadows, pastures, and disturbed soils from sea level to mountainous regions. The species has been widely naturalized throughout North America, particularly in cooler, moister regions of the northern United States and southern Canada.

Suggested Uses

Agrostis gigantea works well as a cool-season turf grass, particularly for athletic fields, pastures, and areas requiring erosion control. In ornamental settings, it serves as an attractive accent grass with its colorful seed heads, suitable for naturalized areas, prairie gardens, and wildlife plantings. The plant's aggressive spreading habit makes it excellent for slope stabilization and areas where quick coverage is desired, though this same characteristic may make it unsuitable for formal mixed borders.

How to Identify

Agrostis gigantea can be identified by its combination of rhizomatous growth habit, flat linear leaves 2-8 mm wide, and distinctive reddish-purple panicles in summer. Key distinguishing features include the open, branched flower heads that are larger and more robust than other Agrostis species, and the plant's ability to form dense colonies through underground rhizomes. The seed heads initially appear green but mature to the characteristic reddish-purple color, and the ligule (membrane where leaf meets stem) is typically 2-6 mm long and truncate.

Appearance

Bloom Information

late spring to early summer

Detailed Descriptions

Flower Description

green maturing to reddish-purple

Foliage Description

medium green

Growing Conditions

Sun Requirements

full sun to partial shade

Soil pH

5.5-7.5

Water & Climate

Water Needs

moderate

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Agrostis gigantea requires minimal maintenance once established, preferring consistent moisture but tolerating periods of drought. Water regularly during the first growing season to establish a strong root system, then reduce watering as the plant becomes drought tolerant. Fertilize lightly in early spring with a balanced fertilizer if desired, though the plant typically performs well in average soils without supplemental feeding. In turf applications, mow regularly during the growing season to maintain desired height and prevent excessive thatch buildup.

Pruning

Agrostis gigantea benefits from annual cutting back in late winter or early spring before new growth begins. Cut the entire plant to 2-3 inches above ground level to remove old foliage and encourage fresh growth. In ornamental settings, the attractive seed heads can be left standing through winter for visual interest and wildlife value, then cut back in spring. For turf use, regular mowing throughout the growing season maintains density and appearance.

⚠️ Toxicity Warning

Agrostis gigantea is generally considered non-toxic to humans and most animals. However, as with many grasses, the pollen may cause allergic reactions in sensitive individuals during flowering season. The plant is commonly used in pastures and is safe for livestock grazing.