Rose of Sharon can be used in so many ways. Its adaptability to pruning means it can be grown as an informal deciduous hedge or trained as a tree. To train a young shrub as a tree, clear the stalk of branches to about one foot high and trim the branch tips across the top. Also, because it forms blossoms on the current year’s growth, you can prune most times of the year without risking too many flowers.
If you have a new rose of Sharon, you can just trim back for shaping and cleaning up broken branches between fall and spring before the leaf buds emerge. If you have an overgrown mature shrub, rose of Sharon can be rejuvenated with hard pruning periodically and will bounce back. Hard pruning means removing 1/3 of the height of the oldest trunks for three years until the shrub is lush and full all over.
When to Prune Rose of Sharon
For structural pruning, the best time is when the shrub is dormant. That’s from late fall through early spring, specifically after leaf fall and before bud break of new growth comes out in spring. On a healthy young shrub, you’ll be doing light trimming for shape and encouraging air circulation. On an overgrown shrub, take this opportunity to do a “renewal prune”, cutting the oldest growth by 2/3 or more.
You may lose a few flowers in that section, but the growth will be healthier for years to come. If you miss your window and prune later in spring, you will have sacrificed flowers on the cut branches, but those on the remaining branches will be bigger!
Why Prune Rose of Sharon
The main reason for pruning rose of Sharon is for shaping and health. Rose of Sharon left unpruned for too long can become gangly or overrun their neighbor’s airspace. A well-maintained shrub will be full, with space between branches for excellent airflow. This means removing excess interior branches, any crisscrossing growth, or branches growing the wrong direction. Air circulation will encourage healthy growth, show off the flowers, and discourage airborne fungal disease.
Other reasons to trim might be to create a lush hedgerow, keep the tree shape your young shrub had when you planted it, or just spur growth throughout your shrub for lots of greenery and flowers. You can also take some flowers indoors for a vase!
How to Prune Rose of Sharon
Step 1 – Winter Shaping for Most.
Remove any dead, broken, or crossing branches. Then remove excess branches on the inside of the bush, trying to allow 8-12” between stems. To foster side branching, pinch the growth tips; otherwise, prune to just above a leaf node for general shaping.
Step 2 – Winter Renewal Pruning for Overgrown Shrubs.
On unruly shrubs, cut the oldest stems by 2/3 of their height to a minimum of one foot high. Do not cut more than 1/3 of the overall number of stems. Repeat for three years.
Step 3 – Tree Pruning (optional)
On a small plant, trim side branches to clear the first foot from the ground and allow the canopy to start there. Then lightly trim the tops of branches to above a leaf node to encourage side branching. Shape in winter as in Step 1.
Rose of Sharon Pruning Tips
- Prune while dormant for shaping and air circulation yearly.
- Pruning can be done from fall through early spring, but before leaf break is best.
- Renewal pruning in stages will help older overgrown shrubs.
- Tree training is best done when the shrub is very young, then maintain shape through winter pruning.