Rhaponticum centaureoides
Knapweed, Star thistle
Also known as Centaurea 'Pulchra Major', Leuzea centauroides, Stemmacantha centauroides
- Height × spread
- 0.9m × 0.5m
- Position
- Full sun
- Hardiness
- Cold to -15C (RHS H5)
- Flowers
- Summer
Availability
Please ask in store about availability
Many plants are seasonal. Call 01234 567890 to check current stock.
About this plant
This makes a handsome, large scale rosette of blue-grey leaves from which arises a flower spike in midsummer. The flower head is like a fat, scaly bud that is as exciting as an unopened jewel case, opening to reveal a frothy, vibrant-pink flower. It self-seeds readily which compensates for the fact that it is a relatively short-lived perennial.
- Flower colour
- Pink, Purple
- Foliage colour
- Blue, Grey
- Variegated
- No
- Scent
- No
- Shape
- Dome
- Height
- 0.9m
- Spread
- 0.5m
- Season of interest
- Summer
- Flowers in
- Summer
- Evergreen
- Deciduous
- Garden style
- Seaside garden, Prairie garden, Gravel garden
- Sun or shade
- Likes full sun, tolerates part shade
- Soil type
- Loam (normal), Poor soil, Sandy soil
- Soil pH
- All types
- Drainage
- Well drained soil, Dry soil, Drought resistant
- Hardiness
- Cold to -15C (RHS H5)
- Borders & containers
- Borders
- Use for
- Bee attraction, Butterfly attraction
- Hazards
- No
Spring
Spring - late · Outdoors
Feed with slow release fertiliser
Apply a general purpose slow release fertiliser, spreading it around the root area of the plant as it is coming into growth. (Or apply a liquid feed at regular intervals throughout the growing season.)
This is a simple way to provide a nutrient boost as a single annual procedure.
Spring-Autumn · Outdoors
Water in dry periods
Established plants in the ground can cope with 7-10 days of dryness, and shrubs often manage 2 to 3 weeks. Water one section of the garden thoroughly each day rather than a little everywhere. Check plants in pots more often, especially in hot weather.
Spring - early-mid · Planting
Divide when too large
The plant can be divided if it becomes too large or another plant is required. This may involve physically dividing the clump in two, removing offsets or small bulbs or dividing rhizomes. The new plants can be grown in pots or planted in the ground.