Hibiscus syriacus, or Rose of Sharon is a deciduous flowering shrub, which is blooming all over the Bluegrass right now. The Rose of Sharon is a hibiscus rather than a rose, and is a member of the mallow family, making them a relative to hollyhocks (Harrodsburg, Kentucky’s city flower), cotton and okra. Rose of Sharon typically flowers in late summer to fall when few other shrubs are in bloom, but because of the abnormally hot temperatures early this spring, the blossoms have arrived early.
When planting Rose of Sharon in your garden, select a moist, well-drained site with full sun to light shade. This shrub grows best in zones 5-9, but with winter protection, can survive in zone 4. Rose of Sharon shrubs can grow 8 to 10 feet tall and have a spread of 4 to 6 feet, with the exception of some new cultivars that are bred to stay small. Blooms on Rose of Sharon can be white, red, lavender or light blue, and most bear small, deeply-lobed, leaves.
Rose of Sharon's main selling point is its profusion of blooms. Normally it is the only shrub with a relatively late period of blooming (August), so it offers color when most other shrubs have quit blooming. Rose of Sharon is a heat lover, so it is prized by growers in the southeastern portions of the United States (like the Bluegrass Region), where summer temperatures can soar to over 95+ degrees. This shrub is very drought-tolerant, so it is also great for areas - like the Bluegrass - that have suffered from droughts in recent years. Another thing to remember about Rose of Sharon is don't think it is dead because it does not leaf out early in the spring. Because of its late blooming habit, it is also late sending out spring leaves.
Rose of Sharon is naturally a multi-stemmed shrub, but it can be trained through pruning (in late winter) to have only one main trunk, sometimes giving it the name Rose of Sharon "tree." The easiest way to prune a Rose of Sharon in the shape you prefer is to train it during its first two years. In addition to pruning the shrub into a tree, it can also be trained for espalier (sideways growth along a fence or wall). Since blooms form on the current year's growth, it's best to prune in early spring before new growth starts. Also, in early spring, one third of the wood - the oldest branches and any weak growth - should be cut down to ground level.
Rose of Sharon is very attractive as a specimen plant, but its ability to be shaped so easily makes it perfect as a plant for a hedge row. The main problem with a Rose of Sharon hedge is the fact it is deciduous, so you need to think of this when planning a hedge because it will not provide winter privacy.
Propagating Rose of Sharon: There are several ways to propagate this shrub:
• Transplant small seedlings found growing in your gardens.
• Direct sow seeds outdoors in the fall
• Direct sow seeds after last spring frost
• Sow seeds indoors about 4 weeks before last frost
Beware older cultivars set heavy seed crops, causing them to self-sow in many unwanted places.