Rose of Sharon(Hibiscus syriacus) is a deciduous shrub that will help bring a bit of tropical beauty to more temperate climates. The blooms that arrive later in the summer will help revive your garden after the flurry of spring flowers.
Names for this shrub are Rose of Sharon, althaea, and hardy hibiscus.
USDA Hardiness Zones:
This shrub is suitable for gardens in Zones 5-8.
Size & Shape:
Rose of Sharon grows to approximately 8-12' tall and 6' wide, with a vase shape.
It is best to grow this shrub in full sun, though it can tolerate up to part shade.
Don't be surprised if the leaves arrive after most of your other plants, as they start producing the leaves late in spring. Leaves are 2-4" long, often with 3 lobes, and jagged edges.
The flowers are 2-5" wide, in shades of white, pink, red, blue, purple, and violet. There is often a different spot of color in the middle of the throat.
The fruit are capsules.
Rose of Sharon can be VERY invasive due to the numerous seeds produced in the capsules. Snip them off before they open.
You can also choose one of the newer cultivars that are genetic hybrids - the triploids. These produce few (if any) seed capsules. Cultivars include:
The blossoms of Hibiscus syriacus are edible.
In the UK and Australia, Rose of Sharon refers to Hypericum calycinum, which we know as St John's Wort in the US.
Be careful when using this as a specimen plant - remember that the leaves appear late in spring and the blooms do not show until later in summer. Good for use in a border.
Rose of Sharon is somewhat tolerant of drought conditions.
This is an excellent plant for attracting hummingbirds.
Rose of Sharon grows best in moist, well drained soil that contains lots of organic matter, though happily it is able to tolerate a wide variety of soils.
In the cooler zones (where the temperatures fall below -10F in winter), be sure to mulch around the plant well during the winter season.
If you have hot summers, you are in luck; Rose of Sharon actually prefers the heat, and will bloom better.
Propagation is by cuttings and seeds.
Though it is naturally a multi-stemmed shrub, Hibiscus syriacus can be trained to have a single trunk, looking more like a tree. It can also be trained as an espalier or shaped into a hedge.
Prune as needed to maintain the shape desired. In winter or early spring, last season's growth should be pruned away, which will help produce bigger blooms.
Pests & Diseases:
Unfortunately, Japanese Beetles love the shrub. Other pests include aphids and spider mites.
Diseases include leaf spot, blight, and cankers.
The buds may drop if the plant is watered too much or too little, or if too much fertilizer is applied.