Culture
Best grown in acidic, humusy, organically rich, medium moisture, moisture-retentive but well-drained soils in part shade. Prefers filtered, sun dappled conditions in part shade.
This is a heat tolerant shrub that tolerates the heat and humidity typically found in the deep South. Good soil drainage is essential (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, keep roots cool and stabilize soil temperatures. Although established plants have some drought tolerance, roots must never be allowed to dry out. Acidify soils as needed. Clip off spent flower clusters as practicable immediately after bloom.
Noteworthy Characteristics
Rhododendron flammeum, commonly called Oconee azalea, is an upright, rounded, medium-sized, deciduous azalea that typically matures to 6-8’ tall and as wide. It is a variable species which is native to the Piedmont region of Georgia and South Carolina primarily being found in woodland areas, dry slopes, and stream bluffs. It is probable that John Bartram collected this plant and sent it to England where it was first described by Kew Gardens in 1789.
Funnel-shaped flowers (1 3/4” across) with showy stamens to 2” long bloom in mid-April as the leaves first begin to emerge. Flowers range in color from yellow-orange to orange to red, with a darker splotch on the upper lobe. Flowers appear in large clusters (trusses containing up to 15 flowers). Flowers are not fragrant.
Synonymous with and formerly known as Rhododendron speciosum.
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 the Latin word flammeus meaning flame-like in reference to the bright red flower color on some species plants.
‘Hazel Hamilton’ features bright yellow flowers.
Problems
Rhododendrons and 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. Shrub borders, mixed borders, woodland gardens and shade gardens. Also effective in foundation plantings or as a hedge.