50 year-old Azalea
What, then, is the difference between an Azalea and a Rhododendron? Azalea blooms are most often funnel-shaped and have five stamens. Rhododendron flowers are most often bell-shaped with ten or more stamens. Rhododendrons thrive best in the Upper or Mid-South. If growing requirements are met, Azaleas will do well throughout the entire South and usually are more adaptable to growing conditions than Rhododendrons are. Also, Azaleas generally have much smaller leaves.
Azaleas may be evergreen or deciduous. Evergreen varieties usually have thicker growth. You can tip-pinch them fairly frequently to maintain shape. Do this after flowering ends, up until about the middle of June. Prune deciduous azaleas while they are dormant and leafless. Leaves are somewhat evenly spaced along the branches of both types and have a bud at the base of each leaf. The new growth will sprout from almost any spot a pruning cut is made.
Azaleas like rich, well-drained, acid soil. They should not be allowed to become too dry or too soggy. Planting in heavy clay soil often causes root rot and the collapse of the plant. Planting in alkaline soil will eventually cause chlorosis (yellowing leaves with darker green veins). When Azaleas are planted, the root ball should be slightly above the level of the soil. They have shallow root systems and do not like to have other plants growing at their base.
These plants will absorb water through the foliage, so wet both the leaves and the root zone when you water. In order to help prevent fungal diseases, it is best to water in the morning so that the leaves can dry by afternoon. Drip irrigation does not usually provide enough water to satisfy an Azalea.
Immediately after the blooms fade is the best time to apply mulch and to fertilize with an acid-forming fertilizer, such as a commercial Azalea/Camellia food or cottonseed meal. It is best not to mulch in the fall because the mulch will hold heat in the soil and delay dormancy. Fertilizing before the plant blooms will produce heavy leaf growth with few blooms.
There are many beautiful varieties of Azaleas. The sun and heat tolerance of the different varieties will vary. Check out the ATP database for the names, photos, and proper care of the different varieties. http://garden.org/plants/searc...