Black Knight Butterfly Bush

Black Knight (*Buddleja davidii* ‘Black Knight’) is a vigorous deciduous shrub with arching stems and fragrant deep-purple flower panicles on new growth. Its summer display suits a sunny mixed border or wildlife planting. Give it room to branch because published mature-size estimates differ. ## Flowers and placement The [RHS cultivar profile](https://www.rhs.org.uk/plants/99262/buddleja-davidii-black-knight/details) describes scented deep-purple panicles on current-season growth and lists full sun to partial shade. The [RHS genus guide](https://www.rhs.org.uk/plants/buddleja) identifies Buddleja flowers as a nectar source for butterflies. Monrovia’s [grower profile](https://www.monrovia.com/black-knight-butterfly-bush.html) describes lightly fragrant violet-purple spikes from midsummer into fall and suggests border, container, and accent uses. ## Size and growing conditions Mature size varies across these profiles: RHS gives 2.5–4 m for height and spread, while Monrovia gives 6–8 feet tall by 4–6 feet wide. Allow for the larger range where space is limited. RHS lists chalk, clay, loam, and sand; Monrovia prefers well-drained, fertile soil. ## Maintenance RHS recommends annual pruning, and Monrovia advises pruning in late fall or early spring. Water deeply and regularly through the first growing season, then reduce frequency as the root system establishes. Monrovia notes that clipping spent flowers can promote continued bloom.