Blue flax

Sun

Full sun; flowering is reduced and stems may lean in shade.

Water

Low once established. Water young plants during dry spells; established plants tolerate drought but may stop flowering during prolonged heat and dryness.

Soil

Well-drained sandy, gravelly or loamy soil, including lean and moderately alkaline soils. Avoid waterlogged ground and heavily enriched beds.

Height

1-3 ft (0.3-0.9 m)

Spread

1-1.5 ft (0.3-0.45 m)

Flowers

Late spring through summer; five-petalled pale to sky-blue flowers, often opening in the morning and dropping their petals later that day.

Foliage

Fine, narrow, blue-green to grey-green leaves spaced along slender, branching stems. Usually dies back in cold winters; some basal growth may persist in mild climates.

Growth

Moderate to fast; plants raised from seed may flower in their first year.

Care needed

Low

• Pollinators
• Drought tolerant
• Cold hardy
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.4 ft (0.42 m)

3. After 2 years

   1.8 ft (0.55 m)

4. After 3 years

   2 ft (0.6 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

the US and Canada

Growth rate

Fast

• Water after planting and during dry spells in the first growing season, letting the soil dry between waterings.
• Avoid routine feeding; rich soil encourages soft, floppy growth.
• Keep the crown free of thick organic mulch; use a light gravel mulch where drainage is good.
• Leave a few seed capsules to ripen if you want replacement plants, and remove unwanted seedlings while small.
• Grow in an open, sunny position rather than staking plants that have become weak in shade.

Pruning. After the main flowering flush, lightly shear spent flowering stems to tidy the plant and encourage possible repeat bloom. If you want seedlings, leave some stems until the capsules ripen, then cut dead growth back in late winter or early spring.

Late winter

Cut away dead stems before new growth develops, leaving any healthy basal foliage.

Spring

Direct-sow seed in a prepared, well-drained bed, or plant young plants without disturbing their roots.

Late spring

Thin crowded seedlings and water new plants during dry spells.

Summer

Lightly shear faded flowering stems, keeping a few uncut if you want seed.

Early autumn

Collect dry, brown seed capsules before they split, or let seed fall naturally.

Autumn

Direct-sow fresh seed and check that winter rain can drain away from the crowns.

• Scatter through a sunny meadow planting with fine-textured grasses for a light blue seasonal haze.
• Plant in loose groups in gravel gardens, where the fine foliage softens stones and paths.
• Combine with yellow-flowered perennials for a clear blue-and-yellow contrast.
• Use near the front or middle of an informal border, allowing neighbouring plants to fill gaps as individual plants age.

Garden styles it suits: Wildflower, Native meadow, Dry gravel garden, Desert / xeriscape, Pollinator garden and Cottage garden.

Plant it with: Prairie dropseed, Blue grama, Yarrow, Lanceleaf coreopsis, Blanket flower and Purple prairie clover.

Wildlife: Flowers provide pollen and nectar for bees and other flower-visiting insects. It is especially useful in open, sunny plantings within its native North American range.

• Crown or root rot in wet soil: improve drainage or move plants to a raised, gravelly bed; avoid frequent watering.
• Floppy stems and poor flowering: provide full sun and stop high-nitrogen feeding.
• Aphids on soft shoots: dislodge small colonies with water and leave predators such as ladybirds undisturbed.
• Plants disappearing after a few years: this is naturally short-lived; allow some self-seeding or sow replacement plants.

Treat the seeds and foliage as potentially toxic if eaten: blue flax contains cyanogenic compounds that can release cyanide. Substantial ingestion may cause serious poisoning in people or animals, including horses; species-specific poisoning information for cats and dogs is limited. Do not use it as food or livestock forage, and seek medical or veterinary advice after significant ingestion.

• Perennial flax (Linum perenne)

  This Eurasian species is extremely similar and is often confused with blue flax in cultivation. Flower colour and general habit are not reliable distinctions; confirmed seed provenance or a botanical key may be needed.

• Common flax (Linum usitatissimum)

  The flax grown for linseed and fibre is an annual, often with a more upright habit. It completes its life cycle after setting seed rather than regrowing from a perennial crown.

• Scarlet flax (Linum grandiflorum)

  Usually has larger, red flowers, though other flower colours exist, and grows as an annual rather than a perennial.

Linum is the Latin name for flax, and lewisii honours Meriwether Lewis of the Lewis and Clark expedition.

Propagation. Usually grown from seed. Direct-sow in autumn or early spring, covering lightly; winter chilling can improve germination. Transplant seedlings while small because established plants resent root disturbance, and division is generally less successful than sowing.

Accepted botanical name

Linum lewisii

In the US and Canada

Native in Alaska, Canada and the lower 48 states.

Native range

Alaska, Alberta, Arizona, Arkansas, British Columbia, California, Colorado, Idaho, Kansas, Manitoba, Mexico Northeast and Mexico Northwest.

Measured

Soil pH 5.6 to 8.4. Average height 16 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.