Huge white flowers with a red throat and constant blooms make this a summer show plant. The flowers last only one day, but are continuous through the late summer until the first fall frost. The foliage is deep green, large and heart-shaped. The Hardy Hibiscus requires constantly moist soil and will not tolerate dry conditions. Prefers full sun but will need partial shade in hot, humid climates
Hardy hibiscus are perennial and can grow about 6 feet tall. They have oval or spear-shaped fuzzy leaves and bear large, trumpet-shaped, pink or white flowers in the summer. They can be planted in regular garden soil in the autumn or spring. The best perennial Hibiscus is H. Moscheutos (the Rose Mallow or Swamp Hibiscus). It grows natively throughout eastern North America in brackish marshes. This and its related kinds are useful for planting near the sea and for planting in raised parts of bogs as well as for setting in ordinary soils that are not dry. Some of the best hybrids may produce flowers that measure 10 to 12 inches across.
Any ordinary garden soil will do as long as it isn't excessively dry. Large plants may be grown in large pots or tubs, or they may be planted in a bed. H. moschuetoes, the Rose Mallow or Swamp Hibiscus, can be grown in 5- to 20-gallon containers of wet soil or under up to 6 inches of water in a water garden. It should be located in sun or partial shade.
Hardy to zone 5
Seeds can be sown in drills 1 inch deep in light soil in May or June. The seedlings are transplanted, 6 inches apart, in a nursery bed and set in their final positions in the fall. They may also be divided..