Azaleas are part of the rhododendron family and are generally in bloom for about 6 weeks each year, beginning sometime between March and May depending on their location. They prefer partial shade, and soil that is well draining. The key to blooming azaleas is to keep them healthy. If you can do that, they you will enjoy spring blooms every year.
Wait until the blooms have fallen off to do your pruning. While you can pick off dead blooms anytime you want, it is best to wait until the blooms are finished flowering and have dropped before pruning. Prune off any dead branches, down to the green wood. You can also prune to shape, if desired, at this time. Do not prune after mid-summer or you risk cutting off the new buds that are already forming for next spring.
Fertilize azaleas after pruning, which help promote blooms the next year. If you're not pruning you azaleas, then fertilize after the blooms have dropped. Use a slow releasing fertilizer or feed labeled for azaleas on the package. Since there are many brands of azalea feed, follow the dosing instructions. Generally, you sprinkle about a teaspoon of fertilizer around the root area of each plant. Repeat every 8 weeks until mid-September.
Watch out for iron deficiencies. If the leaves begin to yellow and the veins are still dark green, your azaleas are iron deficient. The simplest way to remedy this is to add a granular iron directly on top of the soil. Follow the dosing instructions on the label and your azaleas should return to good health and bloom again the next year.
Watch out for azalea lace bugs, which are flying insects that are very hard to see with naked eye. You know if you have azalea lace bugs if the leaves begin to turn silver or white and on the back you notice black spots. Washing the leaves with water is usually sufficient, however for major infestation, use and insecticidal soap to spray on all sides of the leaves. If that doesn't work, then use a pesticide that contains either dimethoate, acephate, carbaryl, or malathion. Reapplication of any method used may need to repeated every 10 to 14 days in order to keep azalea lace bugs under control.