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Sweet 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.

More information on Rhododendron.

Profile Video:
See this plant in the following landscape:
Cultivars / Varieties:
  • 'Dynamite'
  • 'Georgiana'
  • 'Hot Ginger'
'Dynamite' , 'Georgiana', 'Hot Ginger'
Tags:
#fragrant#hummingbirds#deciduous#poisonous#rain garden#wildlife plant#nectar plant#native bees#shade garden#fall interest#rabbit resistant#specialized bees#deer browsing plant#border planting#pollinator plant#larval host plant#food source summer#food source fall#food source herbage#food source nectar#food source pollen#Piedmont Mountains FAC#Coastal FACW#wet soils tolerant#mammals#fall color red#fall color orange#butterfly friendly#fall color purple#problem for cats#problem for dogs#bee friendly#problem for horses#Audubon#woodland garden
 
Cultivars / Varieties:
  • 'Dynamite'
  • 'Georgiana'
  • 'Hot Ginger'
'Dynamite' , 'Georgiana', 'Hot Ginger'
Tags:
#fragrant#hummingbirds#deciduous#poisonous#rain garden#wildlife plant#nectar plant#native bees#shade garden#fall interest#rabbit resistant#specialized bees#deer browsing plant#border planting#pollinator plant#larval host plant#food source summer#food source fall#food source herbage#food source nectar#food source pollen#Piedmont Mountains FAC#Coastal FACW#wet soils tolerant#mammals#fall color red#fall color orange#butterfly friendly#fall color purple#problem for cats#problem for dogs#bee friendly#problem for horses#Audubon#woodland garden
  • 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.
  • Whole Plant Traits:
    Plant Type:
    Native Plant
    Poisonous
    Shrub
    Woody Plant Leaf Characteristics:
    Deciduous
    Habit/Form:
    Erect
    Open
    Growth Rate:
    Rapid
    Texture:
    Medium
  • 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
  • Fruit:
    Display/Harvest Time:
    Fall
    Summer
    Fruit Length:
    < 1 inch
    Fruit Description:
    Displays from July to October, egg shaped capsule 3/4" long
  • 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
  • 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
  • Stem:
    Stem Is Aromatic:
    No
  • 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
  • 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