Rose of Sharon or shrub althea (Hibiscus syriacus) flowers in the late summer, with large blooms that resemble hibiscus flowers -- unsurprisingly, since it is a member of the hibiscus family. Pruning keeps the plant's size in check and keeps the plant healthy. It takes on a sprawling, shrubby form, so gardeners can either prune annually for a manicured form or let the plant grow. Does this Spark an idea?
Time Frame
Gardeners should prune Rose of Sharon in the early spring, before the plant's leaves unfurl. When the branches are still bare, it's easier to see the wood, which helps you identify unhealthy wood so you can remove it and make cuts in the right places. Since Rose of Sharon blooms on growth from the current season, you aren't reducing the flower display by pruning in spring. Some gardeners may wish to trim the plants a second time in late spring, when the leaves have emerged, to thin out the flowers and promote larger blooms.
Considerations
Rose of Sharon does not need to be pruned annually, and you may wish to allow your shrub to grow into more of a sprawling form, or you may prefer to prune regularly to keep the shape compact. These shrubs naturally average 9 to 12 feet in height and 6 to 10 feet in width. How much and how frequently you trim depends on the size shrub you want.
Geography
Rose of Sharon grows in United States Department of Agriculture Hardiness Zones 5 to 8, and bears summer flowers in hues of white, purple or pink. It grows best in full sun. Native to Asia, this plant makes a nice landscape plant or summer-flowering hedge. This shrub develops a large number of blooms, and may drop several flowers before they bloom, notes Purdue University Extension's B. Rosie Lerner.
Pruning
First, remove broken, bent or dead branches, plus any wood that does not look healthy. Once you've done this, prune out branches that crisscross other branches or grow vertically up, interfering with other wood. Then step back from your plant and visualize the desired shape and size. Prune back the remaining branches to shape the tree, working one branch at a time with pruning shears, not hedge clippers. Clip back to a tissue node or a lateral branch. Rose of Sharon can be pruned back to a height of 2 or 3 feet and continue to thrive.
