Centaurea jacea (Brown knapweed) — Clump forming

Overview

Centaurea jacea is a clump forming herbaceous perennial in the genus Centaurea, part of the Asteraceae family, with deciduous foliage. It typically grows around 1-1.5 metres tall and 0.5-1 metres wide, reaching full size in around 2-5 years. Centaurea jacea grows best in full sun, and tolerates most soils and any pH. Its UK hardiness is rated H7. It is drought resistant and low maintenance. Suggested uses include coastal, cottage and informal garden, wildlife gardens, cut flowers, flower borders and beds and ground cover.

About

Centaurea jacea, brown knapweed or brownray knapweed, is a species of herbaceous perennial plants in the genus Centaurea native to dry meadows and open woodland throughout Europe. In Britain and America, it is often found as a hybrid of black knapweed, Centaurea nigra. Unlike the black knapweed, the flower heads always look as if they are rayed, forming a more open star rather than a brush-like tuft. Mature plants reach roughly 1-1.5 metres tall and 0.5-1 metres wide, carrying deciduous foliage. In the garden it prefers full sun and most soil types. It tolerates soil of any pH, well-drained conditions and south-facing and west-facing aspects.

Wikipedia contributors, CC BY-SA 4.0 — Centaurea jacea

About the genus

Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich.

Wikipedia contributors, "Centaurea", CC BY-SA 4.0 — Centaurea

Growing conditions

Best soil and position for Centaurea

Sunlight: Full sun
Soil type: Chalk, Loam, Sand
Soil pH: Acid, Alkaline, Neutral
Soil moisture: Well-drained
Aspect: South-facing, West-facing
Exposure: Exposed, Sheltered
UK hardiness: H7

Plant details

Centaurea jacea size, habit and characteristics

Plant type: Herbaceous Perennial
Habit: Clump forming
Foliage: Deciduous
Height: 1-1.5 metres
Spread: 0.5-1 metres
Time to full height: 2-5 years
Suggested uses: Coastal, Cottage and informal garden, Wildlife gardens, Cut flowers, Flower borders and beds, Ground cover

Care notes

Pruning and caring for Centaurea jacea

Propagation: Seed sown in pots in a cold frame in spring, Division in spring or autumn
Pest resistance: Generally pest-free
Disease resistance: Powdery mildews

Frequently asked questions

Where is the best place to plant Centaurea jacea?

Centaurea jacea prefers full sun. It suits exposed and sheltered positions.

What soil does Centaurea jacea need?

Centaurea jacea is adaptable and grows happily in most soil types, including chalk, loam and sand. It is happy in soil of any pH. Aim for soil that stays well-drained.