An attractive addition to any garden, a rhododendron shrub grows to become full and thick, producing clusters of blooms in different colours, including shades of pink, white and purple and red. Given proper care, the bush hardly needs heavy pruning, but benefits from light pruning to keep it from invading nearby walkways or pathways. Overgrown rhododendrons may benefit from drastic pruning, commonly called rejuvenation pruning, soon after the bloom period to maintain size and shape.
Remove dead flower clusters, called trusses, using pruning shears. Cut the base of the truss, 1/2- to 3/4-inch above new growth. Grip the stem with the truss firmly while cutting.
Remove dead, diseased or damaged stems from the bush with shears. Diseased stems appear curled, wilted or discoloured. Cut directly below the damaged part of the stem, just above the dormant bud.
Disinfect the pruning shears between cuts by rubbing the blades with a sponge immersed in alcohol. This kills any bacteria and prevents it from spreading to other parts of the bush.
Hold the branch you want to cut and follow it down to the last cluster of leaves. Cut 1/4 inch above the highest leaf in this cluster, using pruning shears. Ideally, shape pruning is done in winter during the plant's dormancy period.
Step back and visualise the shape you want the bush to take, so you cut off branches accordingly. Repeat the process of cutting unwanted branches down to the last whorl of leaves.
Snip off wayward, low-lying and crossing branches down to the last cluster of leaves on each.
Inspect the rhododendron shrub to determine the location of the primary branches. Follow smaller shoots near the top of the plant down to each primary branch. Most rhododendrons feature three or more main branches that arise from the crown.
Run your hand over a primary branch, over the point you want to cut it, to determine the location of a cluster of healthy buds. The buds, called latent buds, are light pink.
Cut the primary branch with a pruning saw, 1/4-inch above the buds. Repeat the process of cutting the remaining branches, staggering their heights so the plant attains a natural form when it regrows.
Maintenance pruning removes unsightly parts and focuses the plant's energy toward vegetative growth. Shape pruning alters the shape of the bush, while rejuvenation pruning drastically cuts old wood and reduces bush size. Shape pruning alters the shape of the shrub and promotes multiple branches at growing points. Rejuvenation pruning is best for rhododendron shrubs that are unattractive, leggy or overgrown.