Centaurea jacea
Brown Knapweed
Taxonomy and growth
- Family
- Compositae
- Genus
- Centaurea
- Life cycle
- perennial
- Height
- 0.6 m
- Fertility
- self fertile
- Flower type
- hermaphrodite
- Pollinators
- Bees, Flies, Lepidoptera, Self
Uses
Medicinal uses
Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.
The root is bitter tonic, diuretic and stomachic[4]. An excellent bitter for treating difficult digestive systems, it is still used in rural areas as a digestive and also to reduce the temperature of feverish children[4]. A distilled water made from the leaves is used as an eye lotion in the treatment of conjunctivitis[4].
- Product or use
- Bitter
- Product or use
- Diuretic
- Product or use
- Ophthalmic
- Product or use
- Stomachic
- Product or use
- Tonic
Environment
- Range
- Europe. Naturalized in Britain.
- Habitat
- Hedgerows, uncultivated land and waste ground[4].
- Light
- full sun
- Shade tolerance
- no shade
- Water
- moderate
- Hardiness
- Zone 6+
- Soil textures
- sandy, loamy, clay
- Soil pH
- acid, neutral, alkaline, very alkaline
- Drainage
- well drained
- Tolerances
- drought
- Tolerates Nutritionally Poor Soil
- No
- Drought
- tolerant
Propagation
Seed - sow April in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and plant them out into their permanent positions in the summer. Division in autumn. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the summer or following spring. This should be done at least once every three years in order to maintain the vigour of the plant. Basal cuttings in spring. Harvest the shoots when they are about 10 - 15cm long with plenty of underground stem. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer.
Cultivation
Succeeds in ordinary garden soil[1][2]. Prefers a well-drained fertile soil and a sunny position[2]. Tolerates dry, low fertility and alkaline soils[2]. Plants are suitable for the wild garden and for naturalising[2]. This species is hardy to at least -15°c[2]. Members of this genus are rarely if ever troubled by browsing deer[3].
References
F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00
Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5
Thomas. G. S. Perennial Garden Plants J. M. Dent & Sons, London. 1990-00-00 ISBN 0 460 86048 8
Chiej. R. Encyclopaedia of Medicinal Plants. MacDonald 1984-00-00 ISBN 0-356-10541-5