Lupinus arboreus blue form, Blue Bush Lupine

Native to coastal areas from Sonoma Co. down to Southern California, the Blue Bush Lupine is distinctive for its racemes of scented blue and purple flowers. The leaves are gray-green and covered with fine, silky hairs. The showy blooms, which appear in spring and continue into summer, are an excellent nectar source for native bees and hummingbirds. Various butterflies use this species as a larval host plant. The seeds are enjoyed by birds.

This purple-flowered shrub is an uncommon form of the typically yellow-flowered Lupinus arboreus. It is native to coastal habitats such as bluffs, dunes and slopes, where it provides erosion control. Grow it in full sun with good drainage and occasional to no irrigation once established. It will get 4–7 ft. tall and 3–4 ft. wide. It takes to annual pruning in the late summer if your desire is to keep a more compact shape. It can self sow more than you’d like. Remove the spires of seedpods before they pop open if you don’t want it to multiply.

It’s not suitable for areas which get very cold in the winter, and not suitable for Mendocino Co. northwards where it can invade natural areas. While similar to Silver Bush Lupine (Lupinus albifrons), it can grow larger and appears to be longer lasting in gardens and open spaces. Much depends on the growing conditions.