Description

Easily grown in average, medium moisture, well-drained soils in full sun. Becomes weedy and sparse with diminished flowering performance if not grown in full sun. Does poorly in wet, poorly draining conditions. Will adapt to clay soil if properly amended. 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 often grow more vigorously, produce superior flowers and maintain better shape if cut close to the ground in late winter each year. Prompt removal of spent flower spikes during the growing season will usually encourage continued bloom until frost. This shrub will naturalize, sometimes aggressively, by self-seeding (seed dispersed by wind), particularly in areas where it does not die back in winter. Where self-seeding is a potential problem, remove spent flower clusters prior to formation/disbursement of seed.