Winter hardy to USDA Zones 6-10. In water gardens, grow in containers submerged in up to 6? of water or on wet banks. Also may be grown in the shallow margins of a pond. Best in organically rich soils in full sun to part shade. Thin clumps as needed. Cuttings will root easily. Cut stems back below water line in fall. Foliage dies back to the rhizomes in winter.