When to plant and prune Michaelmas daisy (aster)
Michaelmas daisy (aster) flowers from early August to late October and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Michaelmas daisy (aster) 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 | mid March to early May | early August to late October | late February to late March |
| South Coast and Channel | mid March to early May | early August to late October | late February to late March |
| Greater London (Urban Heat Island) | mid March to early May | early August to late October | late February to late March |
| South East and Home Counties | mid March to early May | early August to late October | late February to late March |
| East Anglia | mid March to early May | early August to late October | late February to late March |
| Midlands and Lowland Wales | mid March to early May | early August to late October | late February to late March |
| Wales and West Coast | mid March to early May | early August to late October | late February to late March |
| Northern England | mid March to early May | early August to late October | late February to late March |
| Scotland Lowlands and Central Belt | mid March to early May | early August to late October | late February to late March |
| Scotland Highlands and Islands | mid March to early May | early August to late October | late February to late March |
| Northern Ireland | mid March to early May | early August to late October | late February to late March |
| Channel Islands and Isle of Man | mid March to early May | early August to late October | late February to late March |
Growing notes
Single daisies give valuable late nectar; stake anything over 1m before midsummer. The Chelsea chop works especially well on Symphyotrichum novi-belgii, reducing height enough to avoid staking, though results vary from year to year.
At a glance
- Spacing
- 45 cm between plants
- Eventual height
- 120 cm
- Eventual spread
- 60 cm
- Hardiness
- H7
- Sun
- Full
- Frost tender
- No
- Grows in a container
- Yes, 20 litres or more
- Balcony rating
- 3 out of 5
Feeding
Spring mulch of organic matter to hold summer moisture.
Pruning group
Cut the old stems back in early spring; cut asters less severely where basal shoots are already showing.
What usually goes wrong
- powdery mildew, worst on Symphyotrichum novi-belgii
- winter wet
- flopping without support
- congested clumps needing division
Related guides
Timings cross-checked against RHS guidance for michaelmas daisy (aster).