When to plant and prune Cornflower
Cornflower flowers from mid May to early August and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Cornflower 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 March to early May | mid May to early August | mid May to early August |
| South Coast and Channel | early March to early May | mid May to early August | mid May to early August |
| Greater London (Urban Heat Island) | early March to early May | mid May to early August | mid May to early August |
| South East and Home Counties | early March to early May | mid May to early August | mid May to early August |
| East Anglia | early March to early May | mid May to early August | mid May to early August |
| Midlands and Lowland Wales | early March to early May | mid May to early August | mid May to early August |
| Wales and West Coast | early March to early May | mid May to early August | mid May to early August |
| Northern England | early March to early May | mid May to early August | mid May to early August |
| Scotland Lowlands and Central Belt | early March to early May | mid May to early August | mid May to early August |
| Scotland Highlands and Islands | early March to early May | mid May to early August | mid May to early August |
| Northern Ireland | early March to early May | mid May to early August | mid May to early August |
| Channel Islands and Isle of Man | early March to early May | mid May to early August | mid May to early August |
Growing notes
A hardy annual sown in situ in spring or autumn - it flowers in late spring and summer, sets seed and dies in the same year, but self-seeds and returns in meadow-style plantings. Deadhead regularly to prolong flowering. Generally pest-free, though powdery mildew can appear in dry summers. Taller plants benefit from twiggy support. The single, open flowers are among the best annuals for bees.
At a glance
- Spacing
- 25 cm between plants
- Eventual height
- 75 cm
- Eventual spread
- 30 cm
- Hardiness
- H6
- Sun
- Full
- Frost tender
- No
- Grows in a container
- Yes, 10 litres or more
- Balcony rating
- 3 out of 5
Pruning group
Deadhead regularly to prolong flowering, and cut stems for the vase
What usually goes wrong
- powdery mildew
- floppy growth on rich soil or in shade
- aphids
- self-seeding into unwanted places
Related guides
Timings cross-checked against RHS guidance for cornflower.