The rose of Sharon, Hibiscus syriacus, also known as althaea, thrives in full sun and well-draining soil in zones five through nine. Although it is considered a shrub, it is sometimes referred to as a tree because it can grow up to 10 feet tall and 6 feet wide. With good pruning, a rose of Sharon will produce larger flowers in the summer to brighten your garden and fill it with color. Pruning not only encourages new growth, but also directs the growth to the remaining branches.
Look over your rose of Sharon in early spring for new buds that are just starting to fill and swell for the new growing season. The swelling buds will signal pruning time.
Trim away branches by cutting them straight across the stem just above a bud. Clip off any branches stick out, disturbing the shape you want to maintain for your rose of Sharon. Each cut branch should still have two or three buds on it.
Look for suckers and new shoots coming up from the ground and clip them away at ground level. If you leave these shoots, they will begin to rob nutrients and energy from the parent plant.
Add a layer of mulch around your plant 2 to 4 inches deep. The mulch helps your plant maintain moisture and keeps weeds away.
Cut the entire plant back to only 2 to 6 feet tall if it becomes overgrown and barely flowers. If this extreme pruning doesn’t seem to help it, try dividing the plant.