When to plant and prune Crocosmia (montbretia)
Crocosmia (montbretia) flowers from early July to mid September and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Crocosmia (montbretia) 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 late April | early July to mid September | late October to late November |
| South Coast and Channel | late March to late April | early July to mid September | late October to late November |
| Greater London (Urban Heat Island) | late March to late April | early July to mid September | late October to late November |
| South East and Home Counties | late March to late April | early July to mid September | late October to late November |
| East Anglia | late March to late April | early July to mid September | late October to late November |
| Midlands and Lowland Wales | late March to late April | early July to mid September | late October to late November |
| Wales and West Coast | late March to late April | early July to mid September | late October to late November |
| Northern England | late March to late April | early July to mid September | late October to late November |
| Scotland Lowlands and Central Belt | late March to late April | early July to mid September | late October to late November |
| Scotland Highlands and Islands | late March to late April | early July to mid September | late October to late November |
| Northern Ireland | late March to late April | early July to mid September | late October to late November |
| Channel Islands and Isle of Man | late March to late April | early July to mid September | late October to late November |
Growing notes
Plant corms at three times their depth and 10-20cm apart in spring; most cultivars are hardy in a warm, sheltered site but appreciate a mulch in cold gardens. Crocosmia x crocosmiiflora (montbretia) spreads strongly and it is illegal to plant it in the wild.
At a glance
- Spacing
- 15 cm between plants
- Eventual height
- 120 cm
- Eventual spread
- 45 cm
- Hardiness
- H5
- Sun
- Full
- Frost tender
- No
- Grows in a container
- Yes, 20 litres or more
- Balcony rating
- 3 out of 5
Feeding
Fortnightly high-potassium feed for plants in containers; border plants need only a spring mulch.
Pruning group
No pruning beyond cutting back the spent foliage once it dies down in late autumn, or leaving it until early spring to shelter wildlife.
Winter protection
In cold gardens spread a thick layer of garden compost over the corms in late autumn to insulate them.
What usually goes wrong
- red spider mite
- poor flowering when clumps get congested
- flopping of tall types in wet, windy weather
Related guides
Timings cross-checked against RHS guidance for crocosmia (montbretia).