Lupine

Sun

Full sun in cool climates; light afternoon shade where summers are warm.

Water

Keep evenly moist while establishing. Water established plants during dry spells, without leaving the roots waterlogged.

Soil

Moderately fertile, moisture-retentive but well-drained soil, preferably acidic to neutral. Avoid strongly alkaline soil and wet winter ground.

Height

3-5 ft (0.9-1.5 m)

Spread

1-2 ft (0.3-0.6 m)

Flowers

Late spring to midsummer; usually blue to violet-blue, sometimes pink or white. Multicoloured garden lupins are often hybrids rather than the species.

Foliage

Green, palm-shaped leaves divided into numerous narrow leaflets; foliage dies back for winter.

Growth

Fast in spring; usually flowers from its second year when grown from seed.

Care needed

Medium

• Water deeply during dry spells, especially while flower spikes are developing.
• Avoid high-nitrogen feeds; use a light compost dressing in spring on poor soil.
• Apply a thin organic mulch to retain moisture, keeping it clear of the crown.
• Stake tall flower stems early in exposed gardens.
• Leave established clumps undisturbed; their deep roots make division and transplanting unreliable.
• Remove seed pods before they ripen where self-seeding is unwanted.

Pruning. Cut spent flower spikes back to a healthy leaf before pods develop; this may encourage a smaller second flush. Cut dead stems and foliage to ground level in late autumn or late winter.

Late winter

Remove remaining dead growth and check that water is not collecting around crowns.

Spring

Plant young plants while the soil is workable; protect emerging shoots from slugs.

Mid-spring

Add a thin mulch and install discreet supports before stems become tall.

Late spring

Check shoot tips and flower stems for aphid colonies.

Summer

Water during dry weather and remove faded spikes before seed pods mature.

Autumn

Sow seed in pots outdoors for natural winter chilling, where growing this species is appropriate.

• Plant in small groups through the middle or back of a cottage border for upright early-summer colour.
• Pair with hardy geraniums and lady's mantle to soften the bare lower stems.
• Combine blue-flowered plants with white daisies and catmint for a cool-coloured border.
• Use in native plantings within its western North American range, provided local conditions and provenance are suitable.

Garden styles it suits: Cottage garden, English country, Arts and Crafts, Blues and silvers, Pollinator garden and Pacific Northwest woodland.

Plant it with: Hardy geranium, Lady's mantle, Catmint, Shasta daisy, Bearded iris and Yarrow.

Wildlife: Flowers provide pollen for bumblebees and other bees. Its ability to enrich soil with nitrogen can alter native plant communities where it escapes cultivation.

• Slugs and snails eat emerging shoots: inspect on damp evenings, remove hiding places and use locally approved iron-phosphate bait if needed.
• Lupin aphids cluster on stems and distort growth: inspect frequently, squash small colonies or wash them off with water; remove badly infested spikes.
• Powdery mildew coats leaves in dry, crowded conditions: improve spacing, water the soil rather than foliage and remove badly affected leaves.
• Crown or root rot causes wilting and collapse in wet soil: improve drainage, avoid burying the crown and replace badly affected plants.

Toxic to people, cats, dogs and horses if eaten. All parts can contain poisonous alkaloids, with seeds and pods a particular concern; concentrations vary. Significant ingestion can cause weakness, trembling, breathing problems and potentially death. Do not treat garden lupine seeds as edible lupin beans; seek medical or veterinary advice after ingestion.

Where it spreads. Spreads by seed and can form dense stands outside its native range. It is invasive in parts of northern and central Europe, including the Nordic and Baltic countries, and in New Zealand; it also escapes aggressively in parts of eastern Canada, the northeastern United States and Scotland. It is naturalised in parts of southeastern Australia, including Tasmania.

• Wild lupine (Lupinus perennis)

  Usually shorter, with about 7-11 leaflets per leaf rather than the roughly 9-17 of large-leaved lupine; it favours dry, sandy ground in eastern North America. Leaflet counts overlap, so check origin and other features.

• Tree lupin (Lupinus arboreus)

  Forms a woody shrub with persistent branching stems, usually bearing yellow flowers, rather than dying back to the ground each winter.

• Russell hybrid lupins (Lupinus × regalis)

  Often have especially dense spikes in pink, red, yellow or contrasting two-colour combinations. They have large-leaved lupine ancestry, and blue-flowered hybrids may be difficult to distinguish by appearance alone.

Lupinus comes from the Latin lupus, meaning wolf, reflecting an old mistaken belief that lupins robbed soil of fertility, while polyphyllus means many-leaved.

Propagation. Grow from seed, lightly nicking the seed coat and soaking overnight before sowing, or sow outdoors in autumn for winter chilling. Use deep pots and plant out young to limit root disturbance. Seed from plants near other garden lupins may produce hybrids; division is generally unreliable.

Accepted botanical name

Lupinus polyphyllus

In the US and Canada

Native in Canada and the lower 48 states. Introduced in Alaska.

Native range

Alberta, British Columbia, California, Connecticut, Idaho, Maine, Masachusettes, Minnesota, Montana, Nevada, New York and Ontario.

Measured

Soil pH 5 to 5.5. Average height 118 cm.

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