Azaleas are hardy spring-blooming bushes/shrubs that only require minimal sunlight and overall care. However, even the most robust breeds of plants need a little helping hand from time to time if they are to thrive. To that end, take a few easy steps to make certain you are feeding and caring for your azaleas to get the best out of them each year.
Check the pH level of the ground the azaleas are planted in. This can be accomplished with any standard soil test kit. The reason for this is that, unlike many plants which thrive in a pH-neutral soil environment, azaleas grow well in a more acidic soil that is richer in iron. Generally the soil should have a pH of approximately 5.5, otherwise the azalea will often yellow and its growth will be stunted.
Modify the pH of the soil as needed with the addition of an acid-rich plant food. For best results, apply this food to the pre-mulched top soil. Do not work the plant food into the ground, as azaleas have surface root systems that can easily be disturbed by such activity. Continue to recheck the soil's pH balance until the proper level of acidity is attained.
Apply a layer of standard organic plant food once the soil reaches the proper level of acidity. Again, only apply the food to the top of the soil so as not to disturb the surface root systems that are present. As a general rule, 1 cup of organic plant food per foot of branch spread is recommended, though this amount may need to be doubled if the azalea bush has a branch spread measuring over 3 feet across.
Place a layer of mulch over the plant food around the base of the azalea bush. The mulch layer should optimally be roughly 1 inch deep.
Repeat the feedings in both the spring and fall, watering as needed throughout the year. Do not feed the azaleas during the summer months, as this is unhealthy for acid-rich plants.