Plant food, also known as fertilizer, comes in a powdered and liquid formulas. It provides important nutrients to plants and shrubs. Azalea lovers may disagree what, if any, fertilizer should be used for azaleas. Some contend that adding enough organic matter to the soil and a few layers of mulch provide the same benefits as regular fertilization. However, according to Ohio State University Extension Service, fertilization is beneficial to azaleas. (See reference 2).
Azaleas show signs when they are in need of plant food. Signs include pale green leaves, droopy stems, slow growth and leaf drop. Keep in mind that these may also be signs of root rot or other ailments. Fertilizer provides the nutrients azaleas need, but it will not cure or treat plant diseases.
Both slow-release and fast-release fertilizers are available. Slow-release fertilizers are a better choice, as they gradually release nutrients to azaleas. This reduces the risk of damage to the plant, also called "fertilizer burning."
Choose a slow-release fertilizer that is specifically designed for azaleas. This helps ensure the azaleas are getting the proper nutrients at a steady pace. Azalea fertilizers are found in garden centers.
Timing is crucial when feeding azaleas. Apply fertilizer in early spring or late autumn. Applying fertilizer during the summer may result in damage to the leaves and blooms. (See reference 1).
Refrain from feeding newly planted azaleas until they are established. Azaleas are established after showing new branch growth and blooms. Wait until azaleas have finished flowering before feeding.
Azaleas prefer a soil with a pH balance of 4.5-6.0. The best way to learn your soil's pH level is through a soil test. (See reference 3) County extension offices offer soil testing to home gardeners, or you can purchase a pH test kit at a garden center. If the pH balance is incorrect, the soil test reveals which nutrients are lacking. This helps determine the best type of plant food for the azalea, based on the soil's needs.
While fertilizers help azaleas thrive, they are also extremely toxic to pets and children if ingested. Some fertilizers take on a blue color when mixed with water, giving the appearance of a juice or sports drink. Use caution when fertilizing azaleas or any other part of your garden. Always place fertilizers out of reach of children and pets.
Over-fertilizing may result in damage or death to azaleas. Wipe or brush off any excess fertilizer off of azalea leaves. Wash your hands after working with fertilizer.