Although pruning gardenias is sometimes necessary, the shrub generally does a fairly good job of taking care of itself under the correct growing conditions. There are only a few common reasons for pruning gardenias, including aesthetic reasons; to remove dead, diseased or damaged branches; and to prevent the plant from becoming too leggy. It is important to prune gardenias after they have bloomed and the flowers have died off, although this time can be difficult to determine because some varieties have been cultivated to re-bloom throughout the season. While pruning gardenias in the correct way can help them, cutting branches too short, too aggressively or too roughly can hurt or kill the shrub.
One of the most important considerations when pruning gardenias is the time of year when they are actually pruned. For standard varieties, this should be sometime near the end of the summer season or in the early fall. This is the time when the gardenia has finished blooming for the season and will begin storing energy for growth in the spring. There is a window of time between when the current season’s blooms have died off and the next season’s buds are formed when pruning gardenias can be performed. In the case of gardenias that bloom several times during the summer, they should be deadheaded and pruned after the final blooming cycle.
There are three types of branches to look for when pruning gardenias. The first are dead branches, where no new growth will occur. These are pruned not only for aesthetics, but also because they can be a gateway for diseases and pests. The same holds true for damaged stems, which also should be removed. Diseased stems should be pruned to prevent the problem from spreading to the rest of the plant.
Gardenias take well to pruning, in general. The branches that are cut should not be within 6 inches (about 15 centimeters) of the base, because this will make the branches too short to provide any nutrients or energy to the plant, as well as giving diseases and pests a shortcut to the most sensitive area of the gardenia. It also should be noted that the shrub will make new growth on both old, woody brown stems and new green ones, so cutting either type is acceptable, and brown stems that are still supple should not be considered dead.
The type of pruner used when pruning gardenias also can make a difference. The type of pruner that should be used is called a bypass pruner and has two sharp blades that act like a pair of scissors. Anvil or compression pruners should be avoided, because they essentially crush the stems and can leave a shredded cut where diseases can enter. The gardenia also might have trouble healing from such a cut.