Slender annual with sky-blue flowers grown for linen fibre extracted from the stem and for linseed (flax) oil pressed from the seed. The single oldest cultivated fibre crop, in use for at least 30,000 years.
Hardiness ratings
| System | Rating | Temperature range | How to read it |
|---|---|---|---|
| USDA hardiness zone | Zone 4–9 | −34.4 °C to −1.1 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
| RHS hardiness rating | H6 | −20 °C to −15 °C | Plant needs at least this level of cold tolerance |
| Canadian plant hardiness zone | Zone 4–8 | −29 °C to −1 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
| Australian (ANBG) zone | Zone 1–5 | −15 °C to 10 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
As a tender annual, Flax (Linen flax) doesn't overwinter — the zone range shows where the growing season supports it. See the RHS rating for its actual cold tolerance.
Growing notes
- Bast fibre extracted from the inner stem by retting (controlled rotting) then scutching and hackling — the basis of linen cloth
- Fibre and oilseed cultivars are genetically distinct — fibre types are taller and unbranched, oilseed types branch heavily, do not expect a good linen crop from oilseed flax
- Sow in cool early spring — flax does not tolerate hot dry conditions during fibre development
- Self-seeds modestly where conditions suit
Categories
Related plants
Cross-check Flax (Linen flax) against your zones