Brilliant blue annual once common in cornfields, now almost extinct in the wild. Easy to grow from seed and indispensable for pollinator-friendly annual displays.
Hardiness ratings
| System | Rating | Temperature range | How to read it |
|---|---|---|---|
| USDA hardiness zone | Zone 2–10 | −45.6 °C to 4.4 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
| RHS hardiness rating | H7 | down to −20 °C | Plant needs at least this level of cold tolerance |
| Canadian plant hardiness zone | Zone 2–9 | −40 °C and warmer | Zones where it can be grown as an annual — not a frost-tolerance rating |
| Australian (ANBG) zone | Zone 1–6 | −15 °C to 15 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
As a tender annual, Cornflower doesn't overwinter — the zone range shows where the growing season supports it. See the RHS rating for its actual cold tolerance.
Growing notes
- Forage for bees and hoverflies
- Almost extinct in the UK wild by the 1990s as cornfield weed control improved — now mainly seen in cultivated wildflower mixes
- Edible petals — traditional addition to summer salads and herbal teas
Categories
Related plants
Cross-check Cornflower against your zones