Answer: It's difficult to say why your azaleas won't bloom. The most common causes of non-blooming are pruning at the wrong time and a late frost that nips the flower buds just as they are opening. You might also look to see if the environment has changed over the past 15 years. Perhaps trees are shading the plants now where they weren't a few years ago. Or that your azaleas are now competing with other plants for water and nutrients. Azaleas can live 5 or 6 decades and continue to perform well, but the growing conditions must remain perfect for them or they will begin to decline. You might try pruning out the dead branches. This will open the plant up to better light penetration and better air circulation which should increase its vigor.
Best wishes with your azaleas!
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