Buddleja davidii 'Black Knight' is a popular, fast-growing deciduous shrub known for its large, fragrant, deep purple-to-black flower spikes that bloom from summer to fall, attracting pollinators. It typically grows 6 to 8 feet tall and 4 to 5 feet wide, thriving in full sun and well-drained soil. This hardy, low-maintenance, deer-resistant shrub should be pruned back hard in early spring to encourage vigorous new growth and maximum blooms.