Whether referred to as an althea, Rose of Sharon, or a shrub althea, the Hibiscus syriacus L is a perennial deciduous shrub of the Malvaceae (Mallow) family. The Rose of Sharon has several varieties and uses, each with their own characteristics. It is a hardy shrub with a minimal amount of pest or disease problems. The Ohio State University lists a shrub as one that can be weedy or invasive, and if in a naturalized or neglected area, the seedlings will easily spread.
The Rose of Sharon is a medium sized ornamental shrub, growing up to six to twelve feet. It can be limbed into a small tree form. The Ohio State University lists the best time to prune the Rose of Sharon shrub is in February and March before the leaves begin budding on the branches. The shrub blooms on the current year’s growth. Pruning is generally a task done to eliminate dead or undersized branches, and to keep a shrub well shaped.
Pruning of a Rose of Sharon will reduce the number of blossoms, but creates large flowers. One should not be shy about pruning early in the spring. The stems can actually be trimmed back to only two or three buds remaining on the stem. If allowed to grow without pruning, the shrub will create many blooms, but smaller in size as opposed to a shrub that has been pruned. The blossoms are over two inches across.
J Crockett, author of Flowering Shrubs, lists the flowering zones for the Rose of Sharon are zones five to nine, from mid-July to September. It produces few blooms during the first three or four years, but will flower heavily for many, many years. The shrub is often used as borders and hedges.
It is a hardy deciduous species that tolerates polluted cities, back yards, and close to streets, as well as seashore conditions. It prefers full sunlight, but tolerates light shade. It thrives in moist, well-drained soil. J Crockett recommends supplementing the soil with peat moss, leaf mold, or compost. Plant propagation can be accomplished through seeds.
With a minimal amount of work, the Hibiscus syriacus is a hardy plant that brings color to a yard, border or hedge for most of the summer months. If one is not afraid to prune this woody shrub, it can be limbed into a shaped tree. In addition, if a close eye is kept on the Rose of Sharon, it will not be apt to take over an area and become invasive. The shrub may be planted in an area via the seeds or by propagation. It can also be an attraction for butterflies and birds.
Crocket J. 1997. Flowering Shrubs. Virginia: Time-Life Books. 160 p.
Ohio State University. Accessed 11 Mar 2009. Hibiscus syriacus. Pocket Gardener.