To prune a rhododendron, determine what parts of the plant need cutting, remove dead branches and overgrowth, and then use pruning shears to cut old flower clusters. Prune the rhododendron in the early spring before bud formation.
- Examine the plant
Inspect the plant for cosmetic and health issues that may prevent you from doing extensive pruning. If the plant is large, crawl underneath it, and check for dead branches. Prune unhealthy rhododendrons minimally, then inspect their recovery before proceeding.
- Prune the plant
Apply rubbing alcohol to the blades of the pruning shears to ensure clean cuts. Pull off any branches and leaves that can be easily removed by hand. Using pruning shears, cut the old flower clusters half an inch above the new growth. Remove diseased and damaged wood, making sure to cut below the dead section. Overgrown rhododendrons benefit from extensive cutbacks. Choose a few primary branches, then prune around them.
- Shape the plant
As you make top and side cuts, stand back and inspect the plant's shape. Look for branches with multiple leaf whorls, then prune the branch back by cutting 1/4 inch above the top group of leaves. Check that the plant's shape allows for air to circulate through the plant.