Description
Easily grown in average, medium, well-drained soil in full sun. Prefers loose loams. Tolerates some drought. Intolerant of wet, poorly-drained soils. Roots are winter hardy to USDA Zone 5, but top growth is only reliably hardy to USDA Zone 7. Consequently, plants are generally grown as shrubby, soft-wooded perennials north of USDA Zone 7 by pruning stems back hard each year in early spring. Regardless of pruning intentions, stems will often die to the ground in the cold winters of Zones 5 and 6, with roots surviving to push up new stems in spring. Even in warm winter climates where the stems usually survive winter, gardeners frequently still prune the plants back hard in early spring to promote vigorous new stem growth. Flowering is unaffected by spring pruning because plants bloom on new growth. (Courtesy of Missouri Botanical Garden Plant Finder)
