Butterfly Bush Black Knight The Butterfly Bush is very well known with its arching growing habit and scented flowers. Buddleia davidii ‘Black Knight’ produces large racemes of cone-shaped flower clusters that are a deep violet-blue in late Summer. A good shrub for late Summer colour. Attractive to butterflies and bees. Prune hard to control size, shape and encourage fresh flowering growth. Best done in early spring, but additional partial pruning can be done after flowering in autumn. Holds the RHS Award for Garden Merit. Site: Tolerates coastal exposureSoil: Well drained soils, tolerates drought once establishedPosition: Full sunSeason of Interest: Violet-blue flowers in late SummerHardiness: Fully hardyHeight: 10ft (3m) Spread: 10ft (3m)