Azalea enlivens landscapes with brilliant color from spring to midsummer, but it can prove difficult to grow unless optimal conditions are met. Azalea develops shallow roots that are easily damaged by excessive soil moisture. It does not tolerate heat or dry winds and remains vulnerable to sun scorch throughout the winter. It is susceptible to disease and pests and requires trimming to stimulate growth. Proper azalea care and pruning help ensure the plant’s survival.
How to Care for Azalea
Plant an azalea in a cool, partially shaded location with acidic, well-drained soils. Azalea does best under well-spaced trees that provide filtered shade, or planted a few inches above ground level.
Spread a 2- to 3-inch layer of mulch, such as pine bark or pine needles or wood chips, around the plant’s base to the outermost branches. Make a gap between the mulch and the main stem to keep the bark dry. The mulch conserves moisture, evens out soil temperatures and prevents weeds.
Check the moisture level of the rootball and soil. Water the azalea to a depth of 6 to 8 inches with a soaker hose, if the soil feels dry. Reduce water a month before the first frost to harden off the plant. After a few days of frost, water the plant deeply to ensure adequate moisture throughout the dry days of winter.
Fertilize azalea after spring flowering with an acid fertilizer, such as an azalea-camellia mix. Apply the fertilizer according to the manufacturer’s suggested application rate for the size of your azalea.
Watch for signs of petal blight and lacebug. Flowers affected by the fungal disease petal blight appear spotted, then collapse. Treat petal blight with a fungicide. Leaves of azalea plants infested with lacebug turn gray and discolored due to excrement and cast skins. Spray the undersides of the leaves with an insecticidal soap that contains malathion, dimethoate or acephate every 10 days until the infestation is brought under control.
How to Prune Azalea
Remove diseased and declining stems anytime throughout the growing season. Thin or prune an azalea between the flowering period and the beginning of July to minimize the impact on next year’s flowering.
Trim an azalea to maintain the shape of the plant. Head back leggy or spindly stems to the side branch.
Prune an azalea to the desired height. Cut large side branches back to the main branch. Cut the smaller branches in a staggered fashion, making every third to fifth cut deeper to stimulate new growth at the center of the plant.
Rejuvenate overgrown plants by pruning all branches to within 6 to 12 inches of ground level. Some azalea plants do not survive severe pruning or may take several years to grow back.