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Flame Azalea

Rhododendron calendulaceum (rho-doh-DEN-dron kah-len-dew-LAY-see-um)

Family: Ericaceae Native Understory (15-40 ft)

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 .

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 65 attributes.

How it fits the guild

Guild layer 2 - Understory (15-40 ft) Optimal soil pH Acid (<6.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Often confused with Rhododendron cumberlandense Rhododendron flammeum Rhododendron hybrids Rhododendron 'Stonewall Jackson'

Full plant profile

Growing Conditions
Plant type
Native Plant; Poisonous; Shrub
Life cycle
Woody
USDA zones
5a, 5b, 6a, 6b, 7a, 7b
Light
Deep shade (Less than 2 hours to no direct sunlight) | Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
High Organic Matter; Loam (Silt); Sand
Soil pH
Acid (<6.0)
Soil drainage
Good Drainage | Moist | Occasionally Dry
Available space
6-feet-12 feet
NC region
Mountains; Piedmont
Mature size
Height: 4 ft. 0 in. - 15 ft. 0 in. | Width: 8 ft. 0 in. - 10 ft. 0 in.
Maintenance
Medium
Canopy layer
2 - Understory (15-40 ft)
Form & Appearance
Habit / form
Erect
Foliage
Deciduous
Leaf color
Gold/Yellow; Green; Red/Burgundy
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Elliptical; Obovate
Leaf margin
Entire; Serrate
Hairs present
No
Leaf detail
Medium green (1-3” long), elliptic to obovate with yellow-red fall color. They are alternate, simple with either smooth or toothed margins.
Fall color
Gold/Yellow; Red/Burgundy
Flower color
Gold/Yellow; Orange; Pink; Red/Burgundy
Flower value
Showy
Flower form
Raceme
Flower shape
Funnel
Flower size
1-3 inches
Flower detail
Funnel-shaped, usually non-fragrant flowers (2” diameter) that bloom in loose trusses (5-10 flowers per truss) in May-July. The flowers have exserted (protruding) showy stamens. Variable flower color ranges from yellow to orange to red.
Bloom time
Spring; Summer
Fruit color
Brown/Copper
Fruit type
Capsule
Fruit detail
Displays from June to September.
Bark color
Light Brown; Light Gray
Bark detail
Thin and gray-brown with a finely shredded appearance
Wildlife & Ecology
Native status
Native
Origin
Eastern Appalachians, U.S.A.
Wildlife value
Hummingbirds, butterflies and other pollinators are attracted to the nectar.
Attracts
Bees; Butterflies; Hummingbirds; Pollinators; Small Mammals; Specialized Bees
Food & Medicine
Harvest time
Summer
Fruit type
Capsule
Landscape Use
Landscape location
Naturalized Area; Woodland
Landscape theme
Butterfly Garden; Native Garden; Pollinator Garden; Winter Garden
Design feature
Hedge; Specimen
Garden tags
#deciduous #specialized bees #hummingbird friendly #native bees #drought tolerant #nectar plant #rabbit resistant #fire medium flammability #pollinator plant #native garden #NC native #native shrub #butterfly friendly #food source herbage #larval host plant #food source nectar #mammals #food source pollen #food source summer #problem for cats #problem for dogs #problem for horses #Audubon #nectar plant early summer #nectar plant late spring #nectar plant mid-summer #bumblebee friendly #fall interest #winter interest #interesting bark #flowers late spring #flowers early summer #flowers mid-summer #specimen #poisonous #hedge #wildlife friendly #collier preserve tn #cpp #small groups
Problems & Resistance
Insect problems
Azalea Lace Bug; Azalea Plant Bug; Azalea Caterpillar; Azalea Stem Borer; Azalea Leafminer; Azalea Bark Scale; Azalea Whitefly; Arthropod Pests of Azalea; Azalea Pest Management Calendar; Pests of Azalea
Disease problems
Southern Blight of Herbaceous Ornamentals
Problems
Poisonous to Humans; Problem for Cats; Problem for Dogs; Problem for Horses
Resistant to
Rabbits
Fire risk
medium flammability
Poison severity
Low
Poison parts
Bark; Flowers; Fruits; Leaves; Roots; Seeds; Stems
Poison symptoms
While the plants are known to contain toxins, ingestion of moderate amounts of azalea (nectar or leaves) poses little toxic hazard.
Toxic principle
Grayanotoxins
Contact dermatitis
No
Toxicity summary
Low severity poison; parts: Bark; Flowers; Fruits; Leaves; Roots; Seeds; Stems

Planted at Hunnicutt

Nobody’s planted this one yet.