Rose of Sharon - Hibiscus syriacus
|Rose of Sharon|
If you need color in the landscape in late summer and early fall Rose of Sharon may be the plant you are seeking. Sometimes called Althea or Rose Mallow these plants have been in gardens for centuries. Your grandmother may have had one in her yard but even if you consider yourself a cutting-edge gardener there is a Rose of Sharon perfect for your garden.
Because Rose of Sharon is in the Hibiscus family and the flowers are typical of that family there is some confusion when using common names for the plant. It should not be called hardy hibiscus. The Rose of Sharon or althea is a deciduous woody plant, forming a bush or small tree. Hardy hibiscus are herbaceous plants, they die back to the ground each year. Tropical hibiscus of various species are also bushes or trees but they are not hardy in the United States except in zones 8 and higher and are generally kept as potted plants.
Rose of Sharon, Hibiscus syriacus, is native to India and Asia but not to Syria. It has been planted around the world in temperate regions and sometimes naturalizes. The natural shape of the shrub is vase like with many long straight stems rising to a height of about 12 feet. Nurseries and gardeners often prune and train them into a more tree like shape, with a central trunk.
Rose of Sharon makes an excellent tall screen or hedge when planted closely. They are also planted as landscape accents or garden focal points. They are easily pruned to keep them within the boundaries of your garden.
The bark on trunks and stems of Rose of Sharon is pale gray and smooth. The leaves are about 3 inches long with 3 distinct lobes and a coarse toothed margin. They are arranged alternately on the stems. Leaves are green, sometimes tinged with purple or maroon. The flowers are the fall show- the Rose of Sharon leaves fade to dull yellow brown in the fall.
The flowers of Rose of Sharon are produced profusely from late July to hard frost, depending on the variety and planting zone. In the single flowered varieties there are 5 petals forming a circular flower up to 4 inches across. There is a prominent protruding pistil in the center typical of hibiscus flowers. However, many cultivated varieties are now double flowered, looking more like the rose they are named for or like small peonies.
The flowers of Rose of Sharon come in a wide range of colors from white, through shades of blue, mauve, pink and purple. There are bi-color varieties. There are no true red or yellow flowered varieties. Flowers remain open at night. They are attractive to hummingbirds, moths and butterflies.
Flowers turn into brown, 5 chambered seed capsules. Older varieties re-seed freely and some gardeners consider them invasive. Newer varieties, including many double flowered Rose of Sharon are sterile and don’t make seeds.
Growing Rose of Sharon
Rose of Sharon can be grown from seed quite easily, although it may take 2 or more years for them to flower. Some varieties are not available from seeds as they are sterile and are reproduced through cuttings. I recommend gardeners start with plants, which are sold bare root or potted. You will then know what color and type of flowers to expect.
For hedges plant Rose of Sharon about 6 feet apart. Otherwise plant Rose of Sharon as you would any shrub. They will grow in most soil situations, except poorly drained areas. Don’t add amendments to the hole when planting; plant them in the native soil. They prefer full sun, especially in the north, but can take partial shade in the south.
Rose of Sharon blooms on new wood, so prune them for shaping only in winter or early spring while still dormant if you want blooms. Some gardeners prune each branch back to 3 buds to make the flowers larger. If your plant is trained to a tree shape you may want to trim back any branches that grow too long horizontally and remove branches appearing at the trunk base.
A light application of slow release fertilizer in spring as plants begin new growth is helpful for good growth and flowering. Keep plants well-watered as they get established, after that they are pretty drought tolerant. Flowers will be larger in dry years if they are given supplemental watering.
Japanese beetles are fond of Rose of Sharon and can severely damage foliage in some years. Whiteflies and aphids are sometimes problems also and plants should be treated with pesticides if pest numbers get high. Rose of Sharon are occasionally hit with fungal diseases such as rust or leaf spot diseases, but they rarely kill the plant.
If you have a small garden you may want to try a new Rose of Sharon sold by Proven Winners called Purple Pillar®. While this plant gets tall- up to 16 feet- it’s very narrow and columnar, only about 2-3 feet wide. It is covered with lilac purple flowers in late summer.
Edible and herbal uses
Rose of Sharon flowers and leaves are edible. Leaves are cooked as a green when young or added to salad. Flowers are added to salads and both flowers and leaves are made into tea.
In Korean and Asian medicine there are many uses for Rose of Sharon. Leaves are diuretic, expectorant and used for stomach problems. A decoction of the flowers is diuretic, used as an eye wash, and as a treatment for itching and other skin diseases.
Decoctions of Rose of Sharon root bark are mucilaginous and are used for diarrhea, stomach cramps, menstrual problems, as a vermifuge, and externally to treat skin disorders.
I can find no serious toxicity or side effects listed for Rose of Sharon but as with most herbal medicines use carefully until you see how it affects you.