Rose of Sharon Hibiscus

Zones 5-9
 
Clusters of 4-6" full double, peony-like flowers appear in late summer and fall. A large deciduous shrub in mild climates or a vigorous perennial in colder parts of its range. Flowers grow in an array of blue, purple, lilac.
Rose of Sharon is also called Hardy Hibiscus and Shrub Althea in the South. This flowering shrub is part of the Hibiscus genus and is known botanically as Hibiscus Coelestus syriacus. 
Unlike tropical hibiscuses, the Rose of Sharon is deciduous–it will lose its leaves every autumn and regrow in spring.