- Buddleja davidii
Butterfly bush (Buddleja davidii) is a deciduous to semi evergreen shrub that grows up to 5 m tall. Until only recently, this species was celebrated for its robust growth, fragrance, and range of bloom colours, and often recommended for its ability to grow in poor soil and to attract butterflies. Unfortunately, the Butterfly bush has escaped cultivation in southern BC and is now considered an invasive species. Spreading rapidly by wind-born seed, the butterfly bush displaces native vegetation in disturbed, open areas and along coastal forest edges, roadsides, and especially on sunny stream sides and riverbanks.
Butterfly bush is a prolific seed producer; a single flower cluster can produce over 40,000 seeds. Seeds are dispersed by wind and water and may remain dormant in the soil for many years. New plants can even establish from cuttings. These shrubs also alter the nitrogen and phosphorous amounts in the soil, giving it an advantage that displaces native species, particularly in riparian areas. In forests, it competes with Douglas fir seedlings.
Showy flowers of butterfly bush grow in long, spike-shaped clusters in a range of purple to light purple shades, with egg-shaped to lance-shaped leaves that grow up to 25 cm long.
Removal of Butterfly bush is best when it first comes into flower but has not yet produced seeds. Small plants can be easily hand-pulled when the soil is moist. Remove larger bushes by cutting the plant at the base. Dig up the stump and cover it with a thick plastic bag, or mulch to prevent regeneration. Remove new shoots until the rootstock dies, and do not leave stems on the ground, or they may root.
A few native and ornamental alternatives to use instead of the Butterfly bush include varieties such as; Lewis's mock orange, Red-flowering currant, Black chokeberry, Meyer lilac or California lilac. Read more about these alternatives in the Grow Me Instead booklet for BC.