Perennial flax (blue flax) Linum perenne
Perennial flax (blue flax) (Linum perenne) is a deciduous perennial flowering plant in the Linaceae family, native to Dry grassland of central and eastern Europe to Siberia. It grows 30–60 cm (12–24 in) tall and 20–40 cm (8–16 in) wide, wants full sun and low water, and is hardy to about -35 °C (-31 °F). Space plants about 30 cm (12 in) apart.
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Perennial flax (blue flax) at a glance
| Type | Perennial flowering plant, deciduous |
|---|---|
| Family | Linaceae |
| Mature height | 30–60 cm (12–24 in) |
| Mature spread | 20–40 cm (8–16 in) |
| Spacing | 30 cm (12 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Low; drought tolerance high, waterlogging tolerance none |
| Soil pH | 6–8.5 |
| Cold hardiness | About -35 °C (-31 °F) once established (roughly USDA zone 3) |
| Heat stress | Likely above about 34 °C (93 °F) |
| Flowering | from about May for 6–10 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Not grown as food |
| Native to | Dry grassland of central and eastern Europe to Siberia |
| Common in gardens of | 🇬🇧 United Kingdom, 🇩🇪 Germany, 🇫🇷 France, 🇳🇱 Netherlands, 🇵🇱 Poland, 🇷🇺 Russia, 🇺🇸 United States, 🇨🇦 Canada |
Is Perennial flax (blue flax) toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: seeds (unripe), leaves
Contains cyanogenic glycosides like other flaxes; harmless in a garden, but do not eat unprocessed seeds or leaves.
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 Perennial flax (blue flax)
No well-documented helpful pairing. Group it with plants that like full sun and low water.
Questions about Perennial flax (blue flax)
- How far apart should I plant Perennial flax (blue flax)?
- About 30 cm (12 in) apart, centre to centre. A mature plant spreads 20–40 cm (8–16 in).
- Does Perennial flax (blue flax) need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Perennial flax (blue flax) need?
- Low water. Drought tolerance is high and waterlogging tolerance none.
- How cold-hardy is Perennial flax (blue flax)?
- It tolerates about -35 °C (-31 °F) once established, roughly USDA zone 3.
- When does Perennial flax (blue flax) flower?
- From about May for 6–10 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Perennial flax (blue flax) poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people mildly toxic. Contains cyanogenic glycosides like other flaxes; harmless in a garden, but do not eat unprocessed seeds or leaves.
- What grows well with Perennial flax (blue flax)?
- There is no well-documented companion pairing for Perennial flax (blue flax). Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- RHS Find a Plant (plant profiles and growing guides), Royal Horticultural Society
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
Notes and assumptions
- A rock-garden plant: give it gritty, very free-draining soil, full light and a collar of gravel around the neck; winter wet kills it far more often than cold.
- Wiry, arching stems of fine grey-green leaves with silky sky-blue flowers that open each morning and drop by afternoon, a new crop every day for weeks in early summer. Short-lived but self-seeds.
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
- Flax (linseed) Linum usitatissimum
- Sunflower Helianthus annuus
- French marigold Tagetes patula
- English lavender Lavandula angustifolia
- Zinnia Zinnia elegans
- Cosmos Cosmos bipinnatus
- Purple coneflower Echinacea purpurea
- Foxglove Digitalis purpurea