About
Allium caeruleum is a bulbous perennial that can reach heights of 80 cm. Its narrow leaves typically begin to wither as the flowering period approaches. The plant features sturdy stems topped with dense clusters of star-shaped, bright blue flowers that bloom in early summer.
About the genus
Allium consists of bulbous herbaceous perennials characterized by a pronounced onion or garlic aroma. They feature linear, strap-like, or cylindrical leaves that arise from the base. The flowers, which can be star-shaped or bell-shaped, are arranged in an umbel atop a stem that lacks leaves.
Growing conditions
- Sunlight
- Full sun
- Soil type
- Chalk, Loam, Sand
- Soil pH
- Acid, Alkaline, Neutral
- Soil moisture
- Moist but well-drained, Well-drained
- Aspect
- South-facing, West-facing
- Exposure
- Sheltered
- UK hardiness
- H5
Plant details
- Plant type
- Bulbs
- Habit
- Clump forming
- Foliage
- Deciduous
- Height
- 0.5-1 metres
- Spread
- 0-0.1 metre
- Time to full height
- 2-5 years
- Suggested uses
- Cottage and informal garden, City and courtyard gardens, Gravel garden, Patio and container plants, Wildlife gardens
- Native to
- E Europe to China (Xinjiang)
- Fragrance
- Foliage
Care notes
- Cultivation
- Grow in full sun and fertile well-drained soil. It is best to grow in containers where garden soil is heavy clay and prone to saturation over winter. See allium cultivation
- Pruning
- No pruning required, other than to remove old flowered stems and foliage
- Propagation
- Propagate by seed when just ripe or in spring; or propagate by offsets which can be carefully detached by lifting the bulb after flowering has finished. See bulb propagation
- Pest resistance
- May be susceptible to allium leaf miner and onion fly
- Disease resistance
- May be susceptible to onion white rot, and onion downy mildew