Buddleja davidii 'Black knight'

*Deciduous shrub
*3m h x 2m w
*Striking deep purple, fragrant flowers in summer, possibly into autumn too
*Yellow autumn foliage colour
*Full sun needed to avoid leggy growth
*Medium water needs, less once established
*Moist well drained soil
*In harsh winter areas may be herbaceous, can also cut back to ground in winter in warmer areas