Bristly annual herb with brilliant blue star-shaped flowers. Once sown, returns yearly from self-set seed.
Hardiness ratings
| System | Rating | Temperature range | How to read it |
|---|---|---|---|
| USDA hardiness zone | Zone 2–11 | −45.6 °C to 10 °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 1–7 | −15 °C and warmer | Zones where it can be grown as an annual — not a frost-tolerance rating |
As a tender annual, Borage doesn't overwinter — the zone range shows where the growing season supports it. See the RHS rating for its actual cold tolerance.
About Borage
Borage is grown for its startling blue star-shaped flowers, which are edible and were traditionally floated in drinks, and for its value to bees — it refills with nectar unusually quickly, so the same flower is worked repeatedly through a day. The whole plant is covered in stiff bristly hairs that can irritate skin. It is an annual that seeds itself with real enthusiasm and will persist in a garden indefinitely once introduced. The leaves have a cucumber-like flavour when young, though they become coarse and unpleasantly prickly as the plant ages.
Growing notes
- Edible flowers — float them in summer drinks or scatter on salads
- One of the strongest bee plants for any temperate vegetable garden
Categories
Related plants
Cross-check Borage against your zones