According to the University of Florida, summer-blooming Rose of Sharon (Hibiscus syriacus) is a slow-growing shrub that can reach heights of 8 to 10 feet, with a width of 10 feet. Hardy from U.S. zone 5b to 9A, it tolerates winter temperatures as low as -15 degrees F. Allowed to spread, Rose of Sharon makes an outstanding hedge. With pruning, it works as a long-flowering small tree. Rose of Sharon cultivars in a host of colors are widely available at plant nurseries.
Blue and Purple
Developed in England, Blue Chiffon Rose of Sharon has sky-blue outer petals surrounding a central cluster of smaller delicate lavender petals with a red eye. Producing a wealth of blooms from July until the end of September, Blue Chiffon helps gardens transition from summer to fall. Forgiving of summer heat and humidity, it's a great choice for southern gardens. Hard early-spring pruning every three years will result in bigger blooms.
Attaining heights of up to 12 feet, reddish-purple Arden's Rose of Sharon makes an excellent upright shrub. With pruning or training, it also functions as a tree or espalier planting against a trellis or wall. Arden's single flowers, appearing from early summer until fall, have maroon blotches at their centers. Pruning is necessary only to free the plants of dead branches or for shaping.
Diana Rose of Sharon produces pure white yellow-stamened single blossoms from August to mid-autumn. The flowers make an excellent contrast to the shrub's dark green triangular-toothed leaves. Diana grows up to 12 feet tall, appreciating sun but not fussy about soil. Like most Roses of Sharon varieties, it withstands high heat and humidity without difficulty.
The Jeanne d'Arc Rose of Sharon produces double clear-white flowers against a background of deep green diamond-shaped leaves. Like Arden, Jeanne d'Arc flowers from late summer into mid-autumn, and produces only a few seedpods. Prune to shape or remove dead and dying branches.
Aphrodite Rose of Sharon has striking deep pink blooms with contrasting dark red eyes. Its single blooms have a striking effect when paired with Blushing Bride Rose of Sharon, with dense double-pale pink blooms that gradually fade to white. Both Aphrodite and Blushing Bride have exceptional flowering seasons.
Blushing Bride's first 4-inch flowers appear in spring, followed by Aphrodite's in early summer, and both continue blooming until to mid-fall. Blushing Bride appreciates regular watering. Their long vase life makes its branches desirable as cut flowers. Blushing Bride also tolerates pollution levels that make some areas unsuitable for other shrubs.