Culture
Best grown in light, acidic, sandy, well-drained soils in part shade in USDA Zones 5-8 (maybe 6-8). Tolerates well-drained humusy loams. Tolerates full sun in moist cool locations, but prefers a sun dappled shade or high open part shade. Foliage may scorch in full sun if soils are not kept uniformly moist. Consistent moisture is best, but soils must drain well (doesn’t like “wet feet”). Poor drainage inevitably leads to root rot, therefore raised beds/plantings should be considered in heavy clay soils such as those present in much of the St. Louis area. Roots must never be allowed to dry out. Acidify soils prior to planting and thereafter as needed. Site in locations protected from strong winter winds (flowers can be damaged by late spring frosts). Root systems often benefit from a good mulch (wood chips, bark or pine needles) for retention of moisture, stabilization of soil temperatures and winter protection. Clip off spent flower clusters immediately after bloom as practicable.
Noteworthy Characteristics
Rhododendron atlanticum, commonly known as coast azalea, is a compact, loosely-branched, stoloniferous, suckering, deciduous shrub that typically matures to 2-3’ tall and as wide, but infrequently rises to as much as 6’ tall. Plants which mature to 1-2’ tall are often commonly called dwarf azalea in recognition of their small size. Elliptic to obovate blue green leaves (to 2 1/2” long) have bristly-ciliate margins and blunt to rounded tips. White flowers (to 1.5” long), sometimes flushed with pink, bloom in clusters of 3-13 in April at the time of or slightly before the appearance of new leaves. Corolla (to 1 3/4” long) is covered with sticky glands. Stamens protrude well beyond the corolla mouth. Flowers have a strong musky fragrance. This azalea is native to coastal plain areas from New Jersey and Pennsylvania south to Georgia. Plants are often seen growing in dense colonies in the wild, particularly in sandy soil areas, but are much less inclined to aggressively colonize in landscape plantings, particularly when grown in heavier soils.
This species is often used in azalea breeding programs because of its potent flower fragrance.
Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. Transferred from the Greek name for Nerium oleander.
Specific epithet comes from Latin meaning near the Atlantic Ocean in reference to the coastal plain native habitat of this shrub.
Azalea means dry in reference to a reported preference some azaleas have for dryish soils.
Problems
Azaleas are susceptible to many insect and disease problems, including but not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew, aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. A healthy plant in the proper environment with proper care should have limited problems, however.
Uses
Group or specimen for shrub borders, mixed borders, open woodland gardens, native plant gardens and open shade gardens. Effective near patios and as a specimen around the home.