Rhododendrons are shrubs that produce large springtime blooms. Typically in shades of pink or lavender, the blooms of some varieties of rhododendrons are yellow, white or mixed colors. Suitable for a wooded landscape setting, the shallow-rooted rhododendron likes loamy, slightly acidic soil. With the potential of reaching up to 8 feet tall and wide, it can be helpful to prune rhododendrons to keep them within the landscape's design.
Prune rhododendrons in early spring as new growth appears. Cut or pinch back new shoots when they are about 1 inch long to encourage branching and make the rhododendron fuller with more bloom potential the following year.
Cut the blooms after they fade. Make the cut at a 45-degree angle about 1/4 inch above the leaf rosette, which is the point where several leaves appear in a circle around the stem.
Prune old, overgrown rhododendrons heavily if the shrub becomes too woody, with sparse leaves, large gaps between foliage or few blooms. In the spring, use loppers to cut about one-third of the branches. During the next two springs, remove another one-third of the branches so by the beginning of the fourth year, all old wood has been removed. An alternative is to cut the entire shrub down to about 6 inches above ground in one application in the spring. This approach should promote a revitalization of the rhododendron over the course of two to three years.