Azaleas, members of the genus Rhododendron, bloom every spring. There are over 10,000 different types of azaleas. The plants offer bright yellow, orange, pink, purple, red, salmon and white flowers. Azalea plants prefer some shading, slightly acidic soil and adequate moisture. The proper care of azaleas ensures that they live a long and beautiful life.

Culture

Choose a variety of azalea hardy to your planting zone. Plant the azaleas in a partially shaded, cool area that provides protection from wind. Winter winds damage the plant and the flower buds that form during the fall. Amend clay soils with generous amounts of compost or well-rotted manure. Amend sandy soils with peat moss. Azaleas require a rich, well-draining soil. Purchase a soil testing kit from a gardening center and test the pH level of the soil. Azaleas prefer pH levels between 4.5 and 5.5. Flowers that turn yellow signal a low pH or iron level in the soil. Add sulfur to the soil to raise low pH levels. If the soil pH level is appropriate, add chelated iron or iron sulfate to the soil to correct the problem.

Fertilizing and Watering

Plant azaleas during the late fall in warm climates or early spring after all danger of frost passes. Gently slice the bottom of the root ball with a sterile knife to encourage roots to spread, establish and grow. Mound any remaining soil so it gently slopes away from the plant. Water the area thoroughly to remove any air pockets in the soil. Keep the soil moist while roots establish but do not keep the area soggy. Too much water leads to root rot. Flowers will begin to fade, turn yellow and wilt with inadequate watering. Azaleas do not typically require fertilizer once they become established. Do not fertilize azaleas with a fertilizer high in nitrogen; this promotes leaf development and takes energy away from flowering. Mulch with a 2-inch layer of finely shredded pine bark or pine needles. Keep the mulch at least 1 inch away from the stem of the azalea plant. Reduce watering 1 month before the first frost to harden the plant off for the winter months.

Pruning

Prune azalea plants as soon as they bloom or before the middle of June. Remove all broken, dead, heavily shaded and weak branches. Cut the branches all the way back to where they split off from a larger branch. Remove any stubs. As the stubs die and break off, they leave the plant susceptible to disease. New growth will occur where stubs have healed. Hard prune old, oversized azalea plants. Hard prune the azalea plant over the course of a few seasons to prevent shock. Cut back the tallest of the branches first. The following year cut the remaining branches to the preferred size. Prune to shape the plant during the third season.

Source:

University of Illinois Extension: Azaleas

Azalea Care

Azalea Society of America