While there are several plants from trees to ground covers that have been called Rose of Sharon, the true one or at least the one more universally known as Rose of Sharon is Hibiscus Syricacus or the Althaea shrub. This is a dream plant for the imaginative gardener. Rose of Sharon can be trained as a single stemmed tree, a wide growing bush or an espalier. They can be used as single specimens in the landscape, as potted plants for the patio, as a colorful addition to shrub borders or as a thick, everlasting, flowering, living fence.
Rose of Sharon are deciduous, upright growing and they burst into bloom in mid-late summer until frost with either single, semi-double or double blossoms about 2 1 /2 -3 inches across in colors ranging from pure white, pink, rose, purple, mauve, red, lavender, violet and some with intriguing contrasting throats and eyes. The leaves are bright green, rather small, only 1- 2 1 /2 inches long and have rough edges or toothed lobes.
Being it is a relation of the tropical Hibiscus and the Hibiscus Moscheutos (Rose Mallow) it comes as no surprise that the flowers of the Rose of Sharon resemble them though they are considerably smaller and less showy. While this is strictly opinion, the single flower form is what most people consider the prettiest of these plants. The flowers open wider, and the contrasting colors either in the eyes or throats is rather striking.
Rose of Sharon are super easy to grow with little required to keep them looking their best. They like heat and are tolerant of drought. They can and do grow in many different soil types but prefer sandy, well draining and rich loam. They don’t take well to clay but are tolerant of that too if enough organic mulch is used around them on a continual basis to improve the soil. They like to be placed away from prevailing winds and may require a bit of protection when plants are young. They grow about 12 feet tall, compact and upright when young. As they get older the branches tend to relax giving the plant a more open air. To encourage bigger blooms late winter pruning is recommended back to two buds.
Some of the newer cultivars recently developed for fewer seed capsule are: “Aphrodite” (Rose-pink with red eyes), “Diana” (White), “Helene” (white with deep red eyes) and “Minerva” (lavender with Mauve-red eyes).
Rose of Sharon, unfortunately, has a few drawbacks. The single flower forms have unattractive seed capsules which have a tendency to self-sow abundantly making it a bit of a nuisance for some gardeners. They dislike swampy regions though they like regular water. They are also rather late to break dormancy so you’ll be waiting a bit in the spring (and almost into the summer for the northern most gardeners) for the leaves to unfurl. In autumn they give nothing in the way of an autumn show. They don’t change at all before the leaves drop.
Aside from all the negatives, the Rose of Sharon is indeed a wonderful plant when in flower with its smallish Hollyhock-type blossoms and the bright green leaves. As a hedge it can’t be beat.