Smooth Azalea Rhododendron arborescens
Other Common Name(s):
- Phonetic Spelling
- rho-doh-DEN-dron ar-bor-ESS-senz
- This plant has high severity poison characteristics.
- See below
- Description
-
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.
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.
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.
- Profile Video:
- See this plant in the following landscape:
- Cultivars / Varieties:
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- 'Dynamite'
- 'Georgiana'
- 'Hot Ginger'
- 'Dynamite'
- 'Dynamite' , 'Georgiana', 'Hot Ginger'
- Tags:
- Cultivars / Varieties:
-
- 'Dynamite'
- 'Georgiana'
- 'Hot Ginger'
- 'Dynamite'
- 'Dynamite' , 'Georgiana', 'Hot Ginger'
- Tags:
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-
Attributes:
- Genus:
- Rhododendron
- Species:
- arborescens
- Family:
- Ericaceae
- Life Cycle:
- Woody
- Country Or Region Of Origin:
- Eastern North America
- Wildlife Value:
- Food source for birds, larval host plant for butterflies and moths.
- Dimensions:
- Height: 8 ft. 0 in. - 20 ft. 0 in.
- Width: 8 ft. 0 in. - 20 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Native Plant
- Poisonous
- Shrub
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Erect
- Open
- Growth Rate:
- Rapid
- Texture:
- Medium
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Cultural Conditions:
- 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 To Plant:
- 12-24 feet
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 4b, 4a, 5b, 5a, 6b, 6a, 7b, 7a
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Fruit:
- Display/Harvest Time:
- Fall
- Summer
- Fruit Length:
- < 1 inch
- Fruit Description:
- Displays from July to October, egg shaped capsule 3/4" long
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Flowers:
- Flower Color:
- Gold/Yellow
- Pink
- White
- Flower Inflorescence:
- Raceme
- Flower Value To Gardener:
- Fragrant
- Showy
- Flower Bloom Time:
- Spring
- Summer
- Flower Shape:
- Tubular
- Flower Petals:
- 4-5 petals/rays
- Flower Size:
- 1-3 inches
- Flower Description:
- 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
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Orange
- Red/Burgundy
- Deciduous Leaf Fall Color:
- Orange
- Purple/Lavender
- Red/Burgundy
- Leaf Type:
- Simple
- Leaf Arrangement:
- Alternate
- Leaf Shape:
- Elliptical
- Hairs Present:
- No
- Leaf Description:
- Lustrous dark green leaves; Bright orange or crimson purple fall color
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Stem:
- Stem Is Aromatic:
- No
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Landscape:
- Landscape Location:
- Naturalized Area
- Patio
- Woodland
- Landscape Theme:
- Butterfly Garden
- Pollinator Garden
- Rain Garden
- Design Feature:
- Border
- Specimen
- Attracts:
- Butterflies
- Hummingbirds
- Pollinators
- Specialized Bees
- Resistance To Challenges:
- Rabbits
- Wet Soil
- Problems:
- Poisonous to Humans
- Problem for Cats
- Problem for Dogs
- Problem for Horses
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-
Poisonous to Humans:
- Poison Severity:
- High
- Poison Symptoms:
- Salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, cardiac failure, difficult breathing, progressive paralysis of arms and legs, coma.
- Poison Toxic Principle:
- Andromedotoxin, Grayantoxin
- Causes Contact Dermatitis:
- No
- Poison Part:
- Bark
- Flowers
- Fruits
- Leaves
- Roots
- Seeds
- Stems
