Calamagrostis Karl Foerster

Description

Calamagrostis ‘Karl Foerster’ – feather reed grass

Botanical name: Calamagrostis x acutiflora ‘Karl Foerster’
Common names: Feather reed grass
Family: Poaceae (grass family)
Plant type: Deciduous perennial grass
Habit: Strongly upright, vertical, clump-forming
Pot size: 2–3 litre pot
Eventual size: Approx. 1.5–1.8m tall × 0.6m spread
Foliage: Upright green leaves forming a narrow clump; deciduous
Flowers: Narrow, feathery flower spikes in early summer, pinkish-bronze at first, ripening to warm golden-buff and standing all winter (June onwards)
Scent: Not scented
Aspect / light: Full sun to light shade
Soil: Most soils, including heavier and clay soils; moist but well-drained; any pH
Hardiness: RHS H7 (very hardy, below −20°C); USDA zones 4–9
Exposure: Open, sunny; tolerant
Native range: Garden hybrid; parent species native to Europe and Asia
Toxicity / pet & child safety: Generally considered non-toxic to people and pets

Calamagrostis ‘Karl Foerster’ is a superb upright feather reed grass with narrow, vertical golden-buff flower spikes that stand from early summer right through winter. One of the most architectural of all grasses.

GardenAdvice notes

A strongly upright, clump-forming deciduous grass, feather reed grass is prized above all for its narrow, vertical habit and early, feathery flower spikes, which give strong architectural structure to a planting. It is a sterile hybrid, so it does not self-seed and never becomes a nuisance, while flowering earlier and standing more stiffly upright than almost any other grass. It is one of the earliest grasses to flower and stands stiffly upright right through winter.

Growing & planting

Plant in spring in most soils in full sun to light shade — it is unusually tolerant of heavier and clay soils and reliable moisture, as well as ordinary borders. Its narrow, vertical shape means it takes up little ground space. Space about 60cm apart. It establishes quickly into a strong upright column.

Care & maintenance

Very low-maintenance. Leave the tall stems and plumes standing through winter for their excellent structure, then cut the whole plant down to the ground in late winter or early spring, before new growth begins. Water while establishing. Divide congested clumps in spring if needed.

Propagation

• Division: Lift and divide established clumps in spring — the reliable method for named forms.

Pests & diseases

Generally trouble-free and robust. Rust can occasionally appear on the foliage in a poor season, but it is otherwise an easy, dependable grass.

Uses in the garden

Superb as a strong vertical accent and structural focal point, in mixed and prairie-style borders, in repeated groups for rhythm, and as a see-through screen; the plumes are excellent for cutting.

Wildlife value

The tall winter stems and seedheads provide valuable structure and shelter for wildlife through the colder months.

Toxicity & safety

Feather reed grass is generally regarded as non-toxic to people and pets.

GardenAdvice tip

‘Karl Foerster’ is the go-to grass for strong vertical structure — it stands like a set of narrow golden exclamation marks from midsummer right through winter, and because it’s sterile it never seeds around. Plant it in a repeated row or group for real rhythm and impact, and don’t cut it down until late winter, as the upright winter silhouette is one of its best features.

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