Hibiscus plants are showy, flowering shrubs, trees or vines that can be classified as either annuals or perennials. There are around 300 species of hibiscus, according to the University of Minnesota. One of the most popular is H. rosa-sinensis, or the common tropical hibiscus. While many of these plants, such as the wild hibiscus, are not suitable for training into a tree shape, most of them are able to grow as a small tree if properly pruned.
Wait until early spring, before leaf-out, and prune the plant back to one strong, thick, vertical stem. Cut it back to as little as a third of the plant's original size. Insert a cane (hollow piece of bamboo) into the soil next to the stem. Tie the stem to the cane if the plant needs additional support.
Remove all side branches and vertical shoots that sprout along the trunk. Cut each branch at an angle close to the stem but not flush with it. Sterilize the pruning tools to avoid infecting the plant by dipping them into a bucket of bleach between each cut. Leave the branches at the top of the trunk alone to form the canopy of the hibiscus tree.
Continue to prune in this manner each spring until the tree is the desired height. You may have to replace the cane with a taller one as the tree grows. When the stem is thick enough to form a trunk, the cane can be removed to let the tree stand alone. Prune the canopy occasionally after it flowers to maintain a pleasing shape.