Prune a hibiscus in early spring while the plant is still dormant. It is easier to judge where to cut the plant before the leaves grow.
Prune hibiscus by cutting off at least a third of the branches. Look for nodes that signal new growth and cut the branch about a quarter of an inch above one of these nodes. It is best to trim each limb so the shape is even, and lots of new flowers will emerge in the summer. Remove any dead and diseased branches. Drastic pruning will not harm the plant but instead stimulate lush new growth.