Lupinus sericeus

Common Names

Silky Lupine, Pursh's Silky Lupine, Blue-Bonnet Lupine

Summary

Silky lupine is a perennial forb native to western North America, growing upright from a taproot with silky pubescence on stems and leaves. It typically reaches 40–140 cm tall, with basal and cauline leaves palmately divided into 5–9 leaflets; flowers are blue (occasionally white) and borne in short, compact racemes that bloom from June to September. As a nitrogen-fixer, it hosts nectar-seeking pollinators such as bees and hummingbirds, and produces 2–3 cm long legumes after flowering; its habitats include meadows, grasslands, sagebrush communities, and woodlands at elevations around 2100–2600 m.

Propagation is by seed, with physical dormancy requiring heat scarification (hot-water treatment) followed by cold stratification and inoculation with Lupinus-specific Rhizobium; direct sowing on disturbed sites is common, while transplanting container-grown plants is difficult. Establishment is slow and flowering may take 3–5 years after seeding; it tolerates dry, well-drained soils in full sun and is drought tolerant. Uses include rehabilitation of disturbed areas and support for pollinators; it is a host plant for Melissa blue, silvery blue, and Boisduval’s blue butterflies, while seeds are toxic to cattle and sheep.

Lifecycle

Perennial

Height

1.5-4.5 feet

Spread

1-3 feet

Hardiness Zones

Zones 4-5, 8a-10b

Sunlight Requirements

Ideally full sun; tolerates partial shade.

Soil Type

Well-drained, dry, coarse-textured soil

Soil Drainage

Well-drained soils.

Soil pH

7.0-7.5

Bloom Color

Blue (occasionally white)

Bloom Time

Spring and Summer

Foliage Color

Green

Fall Foliage Color

Green

Leaf Lifecycle

Deciduous

Growth Rate

Slow

Seasons of Interest

Spring and Summer

Propagation Methods

Seeds, Cuttings, Division, Caudex sprouting

Attracts Wildlife

Attracts bees, hummingbirds, butterflies, other pollinators, and birds