Rose of Sharon is actually a variety of hibiscus, which is native to Indian subcontinent and other Asian countries. Planting rose of sharon is possible in variety of zones as it is adaptable to multiple climates.
Cute back by 2/3rds in the winter rose of Sharon blooms on the current season's growth it should be pruned in late winter. Next winter remove any new growth from the previous year and an additional third from the existing old growth. Continue this pattern in subsequent years until the hedge reaches about 8 feet tall, which is a more natural height for the shrub and about as short as you should take it.