Why Can’t I Get My Rhododendrons to Bloom?
Why can't I get my rhododendrons to bloom? In sunny spots, approximately 3 yr old plants.
Certified GKH Gardening Expert
It's likely the soil. If soil has too much nitrogen, it will encourage more foliage growth as opposed to flowering, which needs more phosphorus. Use a "bloom booster" fertilizer or add some bone meal to the soil to help add some phosphorus.
I have two types of rhododendrons in my yard. Two have the small leaves and one has a larger leaf. About twice a year I give them a treatment of used tea leaves. My neighbour gives hers used coffee grounds. The two small rhododendrons bloom faithfully every year. The large one every second year. I just spread the tea leaves around the base of the plant. This is also good for holly bushes.