Flax (linseed) Linum usitatissimum
Flax (linseed) (Linum usitatissimum) is an annual flowering plant in the Linaceae family, native to Domesticated in the Fertile Crescent. It grows 60 cm–1.2 m (24 in–3.9 ft) tall and 10–20 cm (4–8 in) wide, wants full sun and moderate water, and is hardy to about -4 °C (25 °F). Space plants about 5 cm (2 in) apart.
Plan Flax (linseed) in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Flax (linseed) at a glance
| Type | Annual flowering plant |
|---|---|
| Family | Linaceae |
| Mature height | 60 cm–1.2 m (24 in–3.9 ft) |
| Mature spread | 10–20 cm (4–8 in) |
| Spacing | 5 cm (2 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Soil pH | 6–7 |
| Cold hardiness | About -4 °C (25 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Flowering | about 7–9 weeks after planting, for 3–4 weeks |
| Days to maturity | About 100 days from planting |
| Wind tolerance | None |
| Pollinator value | Moderate |
| Edible | Yes: seeds (linseed), oil |
| Native to | Domesticated in the Fertile Crescent |
| Common in gardens of | 🇨🇦 Canada, 🇷🇺 Russia, 🇨🇳 China, 🇮🇳 India, 🇫🇷 France, 🇬🇧 United Kingdom, 🇳🇱 Netherlands, 🇦🇷 Argentina, 🇺🇸 United States |
Is Flax (linseed) toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: immature seed pods, raw seeds in quantity
Contains cyanogenic glycosides, mostly in immature pods; ripe seed is eaten widely in moderation.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Flax (linseed)
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Questions about Flax (linseed)
- How far apart should I plant Flax (linseed)?
- About 5 cm (2 in) apart, centre to centre. A mature plant spreads 10–20 cm (4–8 in).
- Does Flax (linseed) need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Flax (linseed) need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Flax (linseed)?
- It tolerates about -4 °C (25 °F) once established, roughly USDA zone 9. As an annual it is usually planted out after the last frost.
- When does Flax (linseed) flower?
- About 7–9 weeks after planting, for 3–4 weeks.
- Is Flax (linseed) poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people mildly toxic. Contains cyanogenic glycosides, mostly in immature pods; ripe seed is eaten widely in moderation.
- What grows well with Flax (linseed)?
- There is no well-documented companion pairing for Flax (linseed). Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade A (A: strong evidence).
- EcoCrop crop environmental requirements, FAO
- GRIN-Global Taxonomy, USDA ARS
Notes and assumptions
- Sky-blue flowers that open for a morning; stems give linen fibre, seeds give linseed oil.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Perennial flax (blue flax) Linum perenne
- Sunflower Helianthus annuus
- French marigold Tagetes patula
- English lavender Lavandula angustifolia
- Zinnia Zinnia elegans
- Cosmos Cosmos bipinnatus
- Purple coneflower Echinacea purpurea
- Foxglove Digitalis purpurea