Many books suggest using them in a shrub border rather than as a specimen plant in the yard. However, I've noticed that plants placed alone develop a much better shape than those crammed in a shrub border. Rose of Sharon grows best in full sun to partial shade and in just about any soil, except extremely wet or dry. The deciduous, three-lobed leaves don't appear until late spring. Plants thrive in hot summers and are hardy in USDA zones 5 to 8.
Flowers appear on new growth, so pruning is best done in late winter or early spring.
Hard pruning, cutting back to three or four buds on each shoot, yields larger but fewer flowers. Little or no pruning produces many smaller flowers. Rose of Sharon Problems Like other mallow family plants, rose of Sharon is a magnet for Japanese beetles. They need to be controlled with sprays or traps. Double-flowered forms are mostly sterile, not producing viable seeds.