When to plant and prune Delphinium
Delphinium flowers from late May to mid July and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Delphinium is grown to the calendar rather than to the frost, so the same dates apply across the whole UK and every region below reads the same. Where a plant’s timings do follow the frost, Plot shifts them from the Midlands and Lowland Wales baseline using Met Office average frost dates.
| Where you are | Plant | In flower | Prune |
|---|---|---|---|
| South West Coast and Cornwall | late March to mid June | late May to mid July | early July to early August |
| South Coast and Channel | late March to mid June | late May to mid July | early July to early August |
| Greater London (Urban Heat Island) | late March to mid June | late May to mid July | early July to early August |
| South East and Home Counties | late March to mid June | late May to mid July | early July to early August |
| East Anglia | late March to mid June | late May to mid July | early July to early August |
| Midlands and Lowland Wales | late March to mid June | late May to mid July | early July to early August |
| Wales and West Coast | late March to mid June | late May to mid July | early July to early August |
| Northern England | late March to mid June | late May to mid July | early July to early August |
| Scotland Lowlands and Central Belt | late March to mid June | late May to mid July | early July to early August |
| Scotland Highlands and Islands | late March to mid June | late May to mid July | early July to early August |
| Northern Ireland | late March to mid June | late May to mid July | early July to early August |
| Channel Islands and Isle of Man | late March to mid June | late May to mid July | early July to early August |
Growing notes
Slugs and snails devour the young spring shoots and are the main thing to control if you want spikes at all. Get supports in place before the growth reaches 30cm, because a tall spike that has flopped cannot be tied back up neatly.
At a glance
- Spacing
- 60 cm between plants
- Eventual height
- 180 cm
- Eventual spread
- 75 cm
- Hardiness
- H5
- Sun
- Full
- Frost tender
- No
- Grows in a container
- Yes, 30 litres or more
- Balcony rating
- 2 out of 5
Feeding
General fertiliser and a mulch in spring, and a liquid feed while the spikes are developing.
Pruning group
Cut faded flower spikes down to ground level after flowering; plants often produce a second, smaller flush in autumn.
What usually goes wrong
- slugs and snails on spring shoots
- wind damage to unstaked spikes
- powdery mildew
- delphinium black blotch
Related guides
Timings cross-checked against RHS guidance for delphinium.