Brown Knapweed
Centaurea jacea
Family: Asteraceae or Compositae
What it is like
Centaurea jacea is a PERENNIAL growing to 0.6 m (2ft). See above for USDA hardiness. It is hardy to UK zone 6. It is in flower from August to September, and the seeds ripen from August to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees, flies, Lepidoptera (Moths & Butterflies). The plant is self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very alkaline soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.
Height (m): 0.6
Where it is found
Hedgerows, uncultivated land and waste ground.
Europe. Naturalized in Britain.
Conservation Status: This taxon has not yet been assessed.
Countries/locations it is found in
Asia: Lebanon, Syria, Turkey. North America: Canada and USA. Europe: Albania, Austria, Finland, France, Hungary, Italy, Netherlands, Norway, Poland, Russian Federation, Spain, Sweden.
How it is used
Food
Rating: 1
The young leaves are cooked as a vegetable.
Medicine
Rating: 1
The root is bitter tonic, diuretic and stomachic. 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. A distilled water made from the leaves is used as an eye lotion in the treatment of conjunctivitis.
Bitter: Increases the appetite and stimulates digestion by acting on the mucous membranes of the mouth. Also increases the flow of bile, stimulates repair of the gut wall lining and regulates the secretion of insulin and glucogen.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Ophthalmic: Treats eye complaints.
Stomachic: Aids and improves the action of the stomach.
Tonic: Improves general health. Slower acting than a stimulant, it brings steady improvement.
Other
Rating: 0
How it is grown
Succeeds in ordinary garden soil. Prefers a well-drained fertile soil and a sunny position. Tolerates dry, low fertility and alkaline soils. Plants are suitable for the wild garden and for naturalising. This species is hardy to at least -15°c. Members of this genus are rarely if ever troubled by browsing deer.
Propagating it: 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.
Best place to grow: Hedgerow; Cultivated Beds;
Habit: Perennial
Hardiness: 5-9
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Dry, moist
Things to keep in mind
This plant can be weedy or invasive. In Washington, USA it is a Class B noxious weed.
Its other names
Local names
Brown knapweed, brownray knapweed