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Smooth Azalea

Rhododendron arborescens (rho-doh-DEN-dron ar-bor-ESS-senz)

Family: Ericaceae Native Understory (15-40 ft)

Smooth azalea is an erect, loosely branched, woody, deciduous shrub in the Ericaceae (blueberry) family and native to eastern North America. In its native habitat, it is found growing in sloped woodlands, along streambanks, and sometimes boggy areas. The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree. It requires full sun to partial shade in sandy soil with an acidic pH. Moist soil with good drainage is preferable. Fast growing and spreading by underground runners, smooth azalea can reach a height and width of 8 to 12 feet, occasionally reaching 20 feet. Its shallow roots do not like cultivation around them, but rather prefer a thick layer of organic mulch that will help maintain moisture and protect against low winter temperatures. Deadhead immediately after bloom to maintain appearance. Smooth azalea offers multiple seasons of interest. Pink or yellow fragrant flowers bloom from late spring to early summer and attract bees, butterflies, and hummingbirds. In the fall the foliage turns bright orange to crimson or purple color. The plant tolerates damage by rabbits but is frequently damaged by deer. Plant smooth azalea in mixed or shrub borders, woodland or open shade gardens, pollinator or rain gardens. 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. Insects, Diseases, and Other Plant Problems: Insect problems include aphids, borers, lace bugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips, and whitefly. Disease problems include but are not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew. Full sun can scorch foliage. While rhododendrons 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 a 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, 59 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.

Full plant profile

Growing Conditions
Plant type
Native Plant; Perennial; Poisonous; Shrub
Life cycle
Woody
USDA zones
4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b
Light
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
Sand
Soil pH
Acid (<6.0)
Soil drainage
Good Drainage | Moist | Occasionally Wet
Available space
12-24 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 8 ft. 0 in. - 20 ft. 0 in. | Width: 8 ft. 0 in. - 20 ft. 0 in.
Growth rate
Rapid
Canopy layer
2 - Understory (15-40 ft)
Form & Appearance
Habit / form
Erect; Open
Texture
Medium
Foliage
Deciduous
Leaf color
Green; Orange; Red/Burgundy
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Elliptical
Hairs present
No
Leaf detail
Lustrous dark green leaves; Bright orange or crimson purple fall color
Fall color
Orange; Purple/Lavender; Red/Burgundy
Flower color
Gold/Yellow; Pink; White
Flower value
Fragrant; Showy
Flower form
Raceme
Flower shape
Tubular
Flower size
1-3 inches
Flower detail
White to light pink fragrant hairy flowers that feel sticky to the touch. Often with long showy pinkish to red stamens from May to July (after new leaves have fully expanded). May bloom sporadically all summer; strong fragrance
Bloom time
Spring; Summer
Fruit size
< 1 inch long
Fruit detail
Displays from July to October, egg shaped capsule 3/4" long
Wildlife & Ecology
Native status
Native
Origin
Eastern North America
Wildlife value
Food source for birds, larval host plant for butterflies and moths.
Attracts
Butterflies; Hummingbirds; Pollinators; Specialized Bees
Host plant for
butterflies and moths
Food & Medicine
Harvest time
Fall; Summer
Landscape Use
Landscape location
Naturalized Area; Patio; Woodland
Landscape theme
Butterfly Garden; Native Garden; Pollinator Garden; Rain Garden
Design feature
Border; Specimen
Garden tags
#shade garden #deciduous #specialized bees #native bees #poisonous #rain garden #nectar plant #rabbit resistant #border planting #pollinator plant #butterfly friendly #food source herbage #larval host plant #food source nectar #mammals #food source pollen #food source summer #Piedmont Mountains FAC #Coastal FACW #food source fall #problem for cats #hummingbird friendly #problem for dogs #problem for horses #Audubon #bee friendly #wet soils tolerant #fall interest #deer browsing plant #fall color purple #fall color red #fall color orange #wildlife friendly #NC native #NC Native Pollinator Plant #woodland #fragrant flowers
Problems & Resistance
Insect problems
Azalea Lace Bug; Azalea Plant Bug; Azalea Leafminer; 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; Wet Soil
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.