Flame Azalea Rhododendron calendulaceum

Flame azalea is an upright, woody, deciduous shrub in the Ericaceae (blueberry) family that typically matures to 4 to 8 feet tall (infrequently to 10 to 15 feet tall) and 8 to 10 feet wide. It is native primarily to woodland slopes and mountain balds in the Appalachian Mountains from Pennsylvania to Georgia. This species is an important parent of many deciduous azalea hybrids. The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree.  The common name of flame azalea is in reference to the purported resemblance of the upright flower buds to candle flames.

Plant flame azalea in full sun to partial or deep shade with moist, well-drained, acidic, loamy or sandy soil.  It does not tolerate dense clay so amend with organic material if necessary. Protect from afternoon sun, which can scorch the leaves.  Rabbit browsing is tolerated well. Prune rhododendrons and azaleas after they bloom to preserve the current season's bloom, and allow time for the plant to produce flower buds for next year's bloom.  Rhododendrons and azaleas set next year's flower buds by mid to late summer. 

The fiery red orange nectar rich flowers appear from late spring to mid-summer and attract pollinators.  The thin, gray-brown bark is showy and adds winter interest in the garden with its finely shredded appearance.

Slow to establish, this plant is ideal to add some bright, warm spring color in a woodland or naturalized landscape. Use it as a specimen or plant it in groups for a shrub border or even as a hedge.  Add it to a pollinator garden where it will attract butterflies, bees, and hummingbirds. 

Fire Risk: This plant has a medium flammability rating. 

Insects, Diseases, and Other Plant Problems:  Insect problems include aphids, borers, lace bugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips, and whitefly.  Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew. This plant is frequently damaged by deer.

While these shrubs remain very popular for landscape use, many cultivars are susceptible to Phytophthora root rot—this leads to leaf loss, reduced vigor, branch dieback, and wilting. Implement good cultural practices first, such as improving drainage with organic matter or berms and avoiding overwatering or overfertilization. However, if you have a site with a history of this disease, consider planting one of the root rot-resistant alternative species. 

The Clemson Cooperative Extension Home and Garden Information Center has a factsheet on common diseases of rhododendron.  

For suitable alternatives, see this video created by Charlotte Glen as part of the Plants, Pests, and Pathogens series.

VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.

More information on Rhododendron.