Crested Hairgrass (Koeleria macrantha) — An Elegant Grass for Wildflower & Ornamental Plantings

Crested Hairgrass is grown for its form rather than its fodder value. A slender, upright perennial, it produces striking spike-like panicles that stand out among other grasses — opening silvery-green before developing purple-tinged spikelets as the season progresses. Reaching anywhere from 10 to 60 cm in height, it’s a plant that earns its place through elegance rather than bulk. Most at home on calcareous soils, it’s best suited to non-aggressive wildflower and ornamental mixtures where it won’t be crowded out by more vigorous neighbours.

What It’s Used For

Crested Hairgrass is primarily used as an ornamental species — adding upright form and visual interest to wildflower borders and naturalistic plantings. It’s a useful component in low-input, non-aggressive wildflower mixes where its delicate character can be appreciated rather than suppressed.

How Long Will It Last?

A perennial species, though its persistence depends heavily on the company it keeps. In aggressive swards with vigorous grass species, it will likely be pushed out over time. In sympathetic, low-competition mixtures it will persist and self-seed reliably.

Key Strengths

• Distinctive upright spike-like panicles — silvery-green turning purple, adding seasonal interest
• Elegant form and texture in ornamental borders and wildflower plantings
• Well-suited to calcareous and infertile soils where more aggressive species struggle
• Low-maintenance in the right setting

Sowing Rate

• Pure stand: approximately 5 g/m²

Management

Best managed as part of a low-input, infrequently cut wildflower or ornamental planting. Avoid including alongside aggressive grass species — it will not compete and will gradually disappear from the sward if overshadowed.

Identifying the Crop

Seed: Small, light yellow to sandy in colour, approximately 4 mm in length.

Vegetative state: Upright plant producing greyish-green leaves from the base. Lower leaves are hairy, becoming hairless on the upper leaves. Ligules are short with a blunt tip, around 1 mm in length.

Mature plant: Dense, spike-like upright panicles reaching up to 10 cm long, opening silvery-green and developing purple tones over time. Flowers June–July. Plant height 10–60 cm.

Works Well With

Sow with other non-aggressive species — fine fescues, Crested Dogstail, and wildflowers suited to calcareous or low-fertility soils. Avoid ryegrass-dominant mixtures.