Culture: Best grown in rich, humusy, medium moisture, well-drained soils in full sun to part shade. Prefers consistent moisture in soils which do not dry out. Not reliably winter hardy in USDA Zone 5 and the northern part of USDA Zone 6 where it should be sited in a protected location. Although rhizomatous, it spreads very slowly. Evergreen in warm winter climates, but foliage may depreciate considerably in colder areas.