Delphinium
Protect emerging spring shoots from slugs from the moment they appear — young growth can disappear overnight otherwise.
Care
Sheltered from strong wind.
Standard border watering.
Fertile, free-draining, humus-rich soil; dislikes waterlogging over winter.
Cut back flower spikes after flowering to encourage a possible smaller second flush; cut all growth to the ground in autumn.
A hungry plant on good soil: a balanced feed with a thick mulch as growth starts, and a liquid feed after the first spikes are cut down to support the second flush. Feed the soil, not just the plant — the mulch also keeps the roots cool.
Basal cuttings in early spring are the classic method: take shoots about 8cm tall with a sliver of the crown attached, choosing solid ones — a hollow shoot will rot rather than root. Division works, but delphiniums resent it.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- AprilStake early with canes or rings — tall spikes snap easily in wind. how ›
- MayFeed as flower spikes develop. how ›
- JulyCut back spent flower spikes for a possible second flush. how ›
- OctoberCut down to ground level once foliage has died back.
Months based on climate: UK. Your choice stays on this device.
- AprilStake early with canes or rings — tall spikes snap easily in wind. how ›
- MayFeed as flower spikes develop. how ›
- JulyCut back spent flower spikes for a possible second flush. how ›
- OctoberCut down to ground level once foliage has died back.
Months based on climate: Northern Italy. Your choice stays on this device.
- MarchStake early with canes or rings — tall spikes snap easily in wind. how ›
- AprilFeed as flower spikes develop. how ›
- JulyCut back spent flower spikes for a possible second flush. how ›
- OctoberCut down to ground level once foliage has died back.
Months based on climate: Central Italy. Your choice stays on this device.
- MarchStake early with canes or rings — tall spikes snap easily in wind. how ›
- AprilFeed as flower spikes develop. how ›
- JulyCut back spent flower spikes for a possible second flush. how ›
- NovemberCut down to ground level once foliage has died back.
Months based on climate: Southern Italy and islands. Your choice stays on this device.
Common problems
How to spot it. Can destroy young shoots overnight in spring.
What to do. Protect emerging growth — the single biggest threat to this genus.
How to spot it. Tunnels in leaves.
What to do. Remove affected leaves.
Popular varieties
Questions
Delphinium: is it hardy?
H5: Hardy in most of the UK, but can struggle in the coldest inland or upland spots. It survives down to −15 °C.
Can it grow in a pot?
Compact varieties in a large pot; tall types are happier in a border with wind shelter.
Delphinium: when do you prune it?
Cut back flower spikes after flowering to encourage a possible smaller second flush; cut all growth to the ground in autumn. In the calendar for UK, pruning falls in July.
Delphinium: when does it flower?
In the climate of UK it flowers in June–August.
When do you feed it?
A hungry plant on good soil: a balanced feed with a thick mulch as growth starts, and a liquid feed after the first spikes are cut down to support the second flush. Feed the soil, not just the plant — the mulch also keeps the roots cool. Feeding months, UK: March, June.