When to plant and prune Lilac
Lilac flowers from early May to early June and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Lilac 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 | early October to late November | early May to early June | early June to late June |
| South Coast and Channel | early October to late November | early May to early June | early June to late June |
| Greater London (Urban Heat Island) | early October to late November | early May to early June | early June to late June |
| South East and Home Counties | early October to late November | early May to early June | early June to late June |
| East Anglia | early October to late November | early May to early June | early June to late June |
| Midlands and Lowland Wales | early October to late November | early May to early June | early June to late June |
| Wales and West Coast | early October to late November | early May to early June | early June to late June |
| Northern England | early October to late November | early May to early June | early June to late June |
| Scotland Lowlands and Central Belt | early October to late November | early May to early June | early June to late June |
| Scotland Highlands and Islands | early October to late November | early May to early June | early June to late June |
| Northern Ireland | early October to late November | early May to early June | early June to late June |
| Channel Islands and Isle of Man | early October to late November | early May to early June | early June to late June |
Growing notes
Dense, powerfully scented panicles in late spring - an old cottage-garden shrub that eventually becomes a small tree, so give it room. Full sun is essential for good flowering. Deadheading the spent panicles improves the following year's display.
At a glance
- Spacing
- 350 cm between plants
- Eventual height
- 450 cm
- Eventual spread
- 400 cm
- Hardiness
- H6
- Sun
- Full
- Frost tender
- No
- Grows in a container
- No
- Balcony rating
- 1 out of 5
Pruning: what to avoid
Lilac flowers on the previous year's wood, so any pruning must be done just after flowering. Remove suckers from below the graft union as soon as they appear or they will take the plant over. Hard renovation is tolerated but costs two or three years of flowers.
Pruning group
RHS pruning group 1: minimal - deadhead and remove weak, dead or crossing shoots after flowering; tolerates hard renovation pruning if the plant has become too big
What usually goes wrong
- lilac leaf-mining moth
- lilac blight
- powdery mildew
- honey fungus
- suckering from the rootstock
Related guides
Timings cross-checked against RHS guidance for lilac.