Culture
Best grown in acidic, humusy, organically rich, moisture-retentive but well-drained soils in part shade. Prefers a sun dappled shade or high open part shade. Foliage may scorch in full sun. Acidify soils prior to planting and thereafter as needed. Plant in a location protected from strong winter winds. 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. Shallow, fibrous root systems (do not cultivate around plants) will benefit greatly from a mulch (e.g., wood chips, bark or pine needles) to help retain moisture and stabilize soil temperatures. Roots must never be allowed to dry out. Clip off spent flower clusters immediately after bloom as practicable. Slowly naturalizes by root suckers.
Noteworthy Characteristics
Rhododendron canescens, commonly called mountain azalea, Piedmont azalea, hoary azalea or Florida pinkster, is a large deciduous shrub that is native to moist woods, swamp margins and along streams from North Carolina to Florida west to Tennessee, Arkansas and Texas. It typically grows to 6-8’ tall in cultivation, but less frequently may grow to 10-15’ tall. It features clusters (5-9 flowers per cluster) of fragrant, funnel-shaped, pink (infrequently white) flowers (1-2” long) in early spring as the foliage begins to emerge. Pistil and stamens of each flower protrude well beyond the corolla in an upward arch. Obovate to elliptic, dull green leaves (to 3” long) are gray-pubescent (canescent) beneath. Flowers give way to woody capsules (to 1/2” long).
Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. Transferred from the Greek name for Nerium oleander.
Specific epithet means with off-white or ashy-gray hairs.
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
Mass, group or specimen for shrub borders, mixed borders, open woodland gardens, native plant gardens and open shade gardens. Also effective in foundation plantings and as a specimen around the home.