Rough star-thistle
Centaurea aspera · Asteraceae
The gardener's calendar
Ideal time to plant rough star-thistle: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous, gray-green, finely cut
- Flowering
- June to September, pink-purple flowers
- Mature size
- 60-80 cm tall, 40-50 cm wide
- Growth
- Fast
- Hardiness
- -15°C, very hardy
- Origin
- Mediterranean basin and Southern Europe
- Soil type
- Well-draining, gravelly, poor to moderate
Care
Watering
Water moderately once established, only during prolonged dry periods. This plant tolerates drought well and fears excess moisture. In Mediterranean or continental climates, natural rainfall is generally sufficient.
Exposure
Place it in full sun, the ideal condition for generous flowering. It also accepts partially filtered sunlight in very hot climates, but produces fewer flowers in shade.
Soil Preparation
Prepare well-draining soil, slightly chalky or neutral. Enrich it with gravel or sand if the ground is too compact. Avoid constantly moist or clay soils that cause root rot.
Pruning and Cleanup
Prune lightly after flowering (September-October) to maintain a compact shape and remove faded flowers. Spring cutting back (March-April) rejuvenates the clump. Regularly clean out dry stems.
Fertilizer
No fertilizer is necessary in properly prepared soil. Excess nitrogen promotes foliage at the expense of flowers. A light compost application in autumn is sufficient.
Health and Prevention
Very hardy and not susceptible to diseases in a well-draining environment. Watch for powdery mildew in case of excessive humidity. Regularly aerate the center of the clump to prevent fungal problems.
Did you know?
The rough centaury bears the name of the centaur Chiron from Greek mythology, who is said to have used this plant to heal his wounds. Its spiny flowers are a feast for butterflies and bees, making it a valuable ally for pollinators in an ecological garden.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
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Tips generated and checked by Viridia — adapt them to your local climate.