Most large-leafed varieties require dappled shade; avoid deep shade or full sun. A sunny spot that receives a few hours of shade is perfect. Azaleas have shallow root systems and need well-drained, humus-rich, moist, and acidic (pH 4.5–6) soil to keep from drying out.
Azaleas require acid soil (pH 4.5-5.5). If you are in doubt about the acidity of your soil, take a sample to the Cooperative Extension Agent in your county for testing.
Now dig a hole about two times the size of your pot and the same depth as the root ball. Set the soil you have dug out aside and mix it compost. Remove the plant from its pot and gently loosen the root ball. Place the plant in the planting hole and replace the soil with the mix and gently pack down the dirt. To avoid planting to deep make sure the plant is at a position with the top most roots at the soil line.
If desired, construct a water basin at the base of the tree about 36 inches in diameter. Azaleas are very shallow rooted. Mulch in the spring & fall time should be about 4-6 inches deep (acid mulch, pine bark or oak leaves). Keep mulch a few inches away from the trunk of the tree. Do not mulch with mushroom compost.
Organic matter added to the soil and an adequate layering of mulch will generally provide azaleas with sufficient nutrients; therefore, frequent fertilizing is often not required. However, if there are low amounts of nitrogen in the soil, applying fertilizer may be necessary in order to prevent a nutrient deficiency. Symptoms of deficiency in azaleas include stunted growth, smaller greenish-yellow leaves, or early leaf drop. Fertilizing of these shrubs should take place in late spring to early fall.
For the first year it is a critical time for your new azalea. It has not had time to establish itself yet and therefore is not as strong as an older shrub. To prevent the plant from dying, it must be watered twice a week on light soil and once a week on clay soil. Be sure to soak the entire root system deeply, this will take about 45-60 minutes.
For best growth and production, azaleas should receive at least one inch of water a week. Since azaleas are so shallow rooted, we recommend that irrigation be installed when you first plant your azaleas. During dry spells, water is mandatory. If not properly watered during dry spells, flowers may be mitigated. Keep at least 4 feet around the shrub clear of grass and weeds, for less competition for water.
In general, do not prune spring-flowering shrubs such as azaleas and rhododendrons. If you need to reduce height, prune after flowering in the spring. Otherwise, just remove dead, damaged, or diseased branches anytime. On young and old plants, simply snap off spent flower stalks by bending them over until they break away from their stems. Be careful not to damage growth buds at the base of each flower stalk.
Insect & Disease Control
Although azaleas are generally free of pests and diseases with proper azalea care, common azalea diseases and problems do exist. Insects that can affect azaleas include lace bugs and spider mites. Lace bugs are more likely to target shrubs that are grown in areas of full sun.
Susceptible to vine weevil, whiteflies, leafhoppers, scale insects, caterpillars, aphids, powdery mildew, bud blast, rust, leafy gall, petal blight. If soil is not sufficiently acidic, root rot and lime-induced chlorosis could occur.