Hardy hibiscus (Hibiscus spp.) Differ from hibiscus because of their cold-hardiness. While tropical hibiscus can simply grow in always warm, frost-free environments, a few hardy hibiscus are cold hardy to U.S. Department of Agriculture plant hardiness zone 4. These hibiscus grow as small trees or shrubs and have saucer-shaped flowers that are large.
Confederate Rose Mallow
Confederate rose mallow (Hibiscus mutabilis), a deciduous hibiscus shrub which grows in USDA zones 7 through 11, is one of several hardy hibiscus mallow varieties. Confederate rose mallow needs full sunlight, well-draining dirt and plenty of water. The shrub can grow up to 8 feet tall and 4 feet wide. The 4- to flowers deepen and open pink in color as the afternoon continues. The flowers bloom in the summer and attract hummingbirds.
Rose of Sharon
Rose of Sharon (Hibiscus syriacus), also known as Althea, is a deciduous shrub which grows up to 10 feet tall in USDA zones 5 through 9. Rose of Sharon can be trained by pruning the plant to grow as a tree. Rose of Sharon is a late-summer bloomer that brings butterflies. The flower color can be pink or white, depending on the cultivar. This hibiscus can be used as a hedge, and can grow in full sun.
Hibiscus moscheutos cultivars include “Kopper King,” “Lord Baltimore” and “Disco Belle Pink.” Hibiscus moscheutos plants grow in USDA zones 4 through 9, as a shrub up to 4 feet wide and tall in full sun and moist soil. The showy flowers bloom in summer to fall. The color is dependent upon the cultivar. “Kopper King” has coppery leaves with 12-inch-wide white or pink flowers with burgundy facilities. “Lord Baltimore” and “Disco Belle Pink” have pink flowers with red centers and dark green leaves.
Texas Star Hibiscus
Texas Star hibiscus”Hibiscus coccineus” grows to 7 feet tall with a 4-foot disperse in USDA zones 6 through 9. The reddish flowers are divided into five segments, providing the plant’s summer flowers a star’s appearance. This woody upright hibiscus attracts butterflies and hummingbirds. It can grow in full sun to partial shade in moist, well-draining soil. Texas star hibiscus is known as scarlet swamp hibiscus, mallow and crazy mallow rose.