Trimming Rhododendrons is not difficult, but understanding how, when, and where to properly trim a Rhododendron will add years of health to its lifespan. The name "Rhododendron" actually refers to nearly 900 species that comprise the genus of Rhododendron. There is great variety in color, shape and size of blossoms and leaves, height and spread of bushes and trees, and flowering season, and are found growing widely throughout the States as well as in Asia, Europe and Australia. Rhododendrons are extremely adaptable to a wide variety of climate, soil, hydration and sunlight conditions, and are grown in their wild as well as hybrid states for commercial resale. They are amongst the very most popular of all the flowering shrubs for use as landscape hedges, borders, and ornamental small flowering trees.
Trim Rhododendrons only right after they have finished flowering for the previous season. Otherwise, there is the risk of trimming away next year's buds, for a result of a non-flowering Rhododendron the following year. Very minimal maintenance pruning to remove damaged or diseased limbs can be done anytime, taking care not to impact healthy growth for future seasons.
Dead or dying blossoms should be "dead-headed," or removed by hand, to encourage new blooms to form while the blooming season is in process. It is very difficult to harm rhododendrons by trimming, and even severely trimmed Rhododendrons will usually grow back. Trim Rhododendrons for uniformity of shape as they are often used as a hedge or border. During trimming, dead or damaged limbs and branches should also be removed. For certain varietals of Rhododendrons that feature larger leaves, it is important to trim branches back only above new wood growth points to avoid stunting future growth. This is not a concern for smaller leaved varietals.