Common Name: butterfly bush
Type: Deciduous shrub
Zone: 5 to 9
Height: 6.00 to 8.00 feet
Spread: 3.00 to 5.00 feet
Bloom Time: June to September
Bloom Description: Very dark purple
Sun: Full sun
Flower: Showy, Fragrant, Good Cut
Tolerate: Rabbit, Clay Soil
Easily grown in average, medium, well-drained soil in full sun. Becomes weedy and sparse with diminished flowering performance if not grown in full sun. Does poorly in wet conditions. In USDA Zones 5 and 6, this plant will often die to the ground in winter and therefore is often grown therein in the manner of an herbaceous perennial. Even if plants do not die to the ground in winter, they usually grow more vigorously, produce superior flowers and maintain a better shape if cut to the ground in late winter each year. Removal of spent flower spikes during the growing season will encourage additional bloom.
'Black Knight' is a butterfly bush cultivar which features almost black flowers. It is a deciduous shrub with an arching, spreading habit which typically grows 6-8' tall if not cut back in late winter and 4-5' tall if cut back. Features spike-like 4-10" long terminal clusters of very dark purple flowers which bloom from June to September and sometimes to first frost. Flowers are fragrant, and, as the common name suggests, very attractive to butterflies. Willowy gray-green foliage. Popular fresh cut flower.
No serious insect or disease problems. Nematodes can be troublesome in the South.
Provides valuable summer and early fall flowers when few other shrubs are in bloom. Best grown in massed plantings in borders, cottage gardens, rose gardens or butterfly gardens. Usually does not make a good single specimen shrub.