"The Butterfly Bush 'Black Knight', Buddleia 'Black Knight', is a vigorous growing shrub that boasts dark purple flower from mid-summer and is a butterfly magnet. This bush flowers summer and fall and is easy to grow. With a name like Butterfly Bush you might expect a plant to be attractive to butterflies. Plant it near a path or patio and the shrub will provide a delightful fragrance for you, too. It's generally pest-free. This plant blooms on new growth and should be pruned back to the ground in spring."