Perennial
Alpine delphinium
Delphinium elatum
An upright perennial with deeply cut leaves and tall blue to purple-blue flower spikes in summer. It needs fertile, well-drained soil, steady moisture and support for taller stems.
- Size
- 0.6–1.8 m high · 0.5–1 m wide
- Light
- Full sun
- Water
- Moderate
- Winter
- Hardy
- Seasonal form
- Dies back
- Maintenance
- High
Before planting
- Choose a sunny, sheltered spot with fertile soil that drains well but holds some moisture.
- Allow roughly 0.5–1 m for the clump. Cool summers suit it better than prolonged heat and humidity.
- Harmful if eaten by people or pets. Wear gloves when handling it and prevent children or animals from chewing plant parts.
Why choose it
- Vertical flower spikes add height and blue colour to a summer border.
- Its open flowers attract pollinating insects, while the deeply divided foliage contrasts with broader leaves.
Care
- Keep the root zone moist while plants establish; water in summer dry spells without leaving the soil waterlogged.
- Support tall stems early and watch young growth for slugs and snails. Remove withered growth in autumn.
- Remove spent flower stems to encourage a possible later flush; repeat flowering depends on growing conditions.
Good to know
- Stems and leaves die back for winter; cold hardiness does not prevent crown rot in persistently wet soil.
- This profile covers Delphinium elatum; Elatum Group hybrids and compact garden series may have different sizes and needs.