Rhododendrons need little regular pruning unless their growth is excessive or they sustain damage or disease. Pruning at the appropriate time is beneficial to control the size and shape of the plant and remove dead or diseased wood. Removing dead flowers will invigorate the plant and encourage more flowers next year. Dis-budding is optional, but will encourage the development of side branches and a better shape.
Break off flower stems as soon as the flowers wilt, before the seeds develop. Remove dead flowers, leaving the young buds at the base of the cluster. This process, called deadheading, encourages flowering next year.
Prune the rhododendron bush in the summer as soon as possible after flowering is complete. Trim the bush to shape it and control the size. Pruning too late in the season can result in a decrease in flowers next year.
Pinch away the terminal leaf buds on the end of new growth to encourage the development of side branches and the formation of a more compact bush. This is known as dis-budding and should be done on new growth and again in the fall.
Remove damaged branches and dead wood as soon as possible. Cart away trimmings and pruned branches. Leaving debris in the area can encourage pests and disease.
Cut back overgrown and out of control rhododendron shrubs severely. Rhododendrons can be rejuvenated by pruning away up to two-thirds of the plant.