Rose-of-Sharon, known botanically as Hibiscus syriacus, is a flowering shrub or small ornamental tree sometimes called the desert rose or althea. According to Colorado State University, Rose-of-Sharon does not require pruning for bloom. Annual pruning each spring will, however, produce fewer flowers of a larger size. Without pruning the plant will simply produce a greater volume of smaller sized blooms. Though considered a slow growing species, very occasional pruning may be needed to reduce the size of the shrub to suit the landscape setting.
Remove any dead, diseased, abrading or otherwise compromised branches by cutting down to healthy wood. Place all cuts just above a leaf node or bud or down to the parent branch, just beyond the slightly swollen branch collar where the two branches intersect. Discard any diseased or insect infested cuttings.
Cut back the tips of the branches to the desired length. Place the cuts evenly around the shrub, following the natural shape of the plant for a natural and polished result.
Grow larger but fewer flowers in early summer by cutting back the branch tips in February or April of each year. Cut back the branches to the desired length by removing no more than one quarter of the entire shrub canopy in any pruning session. Place each cut just past a leaf node or bud.