Allium giganteum
Allium giganteum
The giant allium produces the tallest flower stems of any ornamental onion, reaching 150cm or more. Dense lilac-purple globes up to 15cm wide appear in June atop thick leafless stems. A statement plant for the back of borders. Needs well-drained soil and shelter from strong wind to prevent stems snapping.
Where to plant
Best aspect
Border position
When to plant and expect flowers
Plant
Flowers
How to grow allium giganteum
Plant large bulbs 15-20cm deep in autumn. Needs full sun and excellent drainage. Stake in exposed positions. Foliage dies back before flowers open, so plant among perennials that conceal the base. Expensive bulbs so protect from squirrels with chicken wire.
Soil requirements
Soil type
loam, sand
Moisture
well drained
pH
neutral, alkaline
Aftercare
Allow foliage to die back naturally after flowering. Remove spent flower heads to prevent self-seeding.
Propagation
- Offsets in autumn
- Seed
Wildlife value
Toxicity
All parts mildly toxic. Contains organosulfur compounds causing gastrointestinal upset.
Common problems
- Slugs and snails
- Squirrels digging up bulbs
Similar bulbs to grow
Related guides
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