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Flame Azalea Rhododendron calendulaceum

Phonetic Spelling
rho-doh-DEN-dron kah-len-dew-LAY-see-um
This plant has high severity poison characteristics.
See below
Description

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.

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. 

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:
Four-Season Garden
Cultivars / Varieties:
  • 'Chatooga'
  • 'Cherokee'
  • 'Flame Azalea'
  • 'Richard Beilski'
'Chatooga', 'Cherokee', 'Flame Azalea', 'Richard Beilski'
Tags:
#hummingbirds#deciduous#poisonous#drought tolerant#interesting bark#specimen#wildlife plant#nectar plant#native shrub#native bees#winter interest#fall interest#rabbit resistant#hedges#specialized bees#fire medium flammability#bumblebees#NC native#native garden#pollinator plant#flowers late spring#flowers mid-summer#larval host plant#food source summer#flowers early summer#food source herbage#food source nectar#food source pollen#small group plantings#nectar plant late spring#mammals#butterfly friendly#nectar plant early summer#nectar plant mid-summer#problem for cats#problem for dogs#problem for horses#Audubon
 
Cultivars / Varieties:
  • 'Chatooga'
  • 'Cherokee'
  • 'Flame Azalea'
  • 'Richard Beilski'
'Chatooga', 'Cherokee', 'Flame Azalea', 'Richard Beilski'
Tags:
#hummingbirds#deciduous#poisonous#drought tolerant#interesting bark#specimen#wildlife plant#nectar plant#native shrub#native bees#winter interest#fall interest#rabbit resistant#hedges#specialized bees#fire medium flammability#bumblebees#NC native#native garden#pollinator plant#flowers late spring#flowers mid-summer#larval host plant#food source summer#flowers early summer#food source herbage#food source nectar#food source pollen#small group plantings#nectar plant late spring#mammals#butterfly friendly#nectar plant early summer#nectar plant mid-summer#problem for cats#problem for dogs#problem for horses#Audubon
  • Attributes:
    Genus:
    Rhododendron
    Species:
    calendulaceum
    Family:
    Ericaceae
    Life Cycle:
    Woody
    Country Or Region Of Origin:
    Eastern Appalachians, U.S.A.
    Fire Risk Rating:
    medium flammability
    Wildlife Value:
    Hummingbirds, butterflies and other pollinators are attracted to the nectar.
    Dimensions:
    Height: 4 ft. 0 in. - 15 ft. 0 in.
    Width: 8 ft. 0 in. - 10 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Native Plant
    Poisonous
    Shrub
    Woody Plant Leaf Characteristics:
    Deciduous
    Habit/Form:
    Erect
    Maintenance:
    Medium
  • Cultural Conditions:
    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 To Plant:
    6-feet-12 feet
    NC Region:
    Mountains
    Piedmont
    USDA Plant Hardiness Zone:
    5b, 5a, 6b, 6a, 7b, 7a
  • Fruit:
    Fruit Color:
    Brown/Copper
    Display/Harvest Time:
    Summer
    Fruit Type:
    Capsule
    Fruit Description:
    Displays from June to September.
  • Flowers:
    Flower Color:
    Gold/Yellow
    Orange
    Pink
    Red/Burgundy
    Flower Inflorescence:
    Raceme
    Flower Value To Gardener:
    Showy
    Flower Bloom Time:
    Spring
    Summer
    Flower Shape:
    Funnel
    Flower Petals:
    4-5 petals/rays
    Flower Size:
    1-3 inches
    Flower Description:
    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.
  • Leaves:
    Woody Plant Leaf Characteristics:
    Deciduous
    Leaf Color:
    Gold/Yellow
    Green
    Red/Burgundy
    Deciduous Leaf Fall Color:
    Gold/Yellow
    Red/Burgundy
    Leaf Type:
    Simple
    Leaf Arrangement:
    Alternate
    Leaf Shape:
    Elliptical
    Obovate
    Leaf Margin:
    Entire
    Serrate
    Hairs Present:
    No
    Leaf Description:
    Medium green (1-3” long), elliptic to obovate with yellow-red fall color. They are alternate, simple with either smooth or toothed margins.
  • Bark:
    Bark Color:
    Light Brown
    Light Gray
    Surface/Attachment:
    Shredding
    Bark Description:
    Thin and gray-brown with a finely shredded appearance
  • Stem:
    Stem Is Aromatic:
    No
  • Landscape:
    Landscape Location:
    Naturalized Area
    Woodland
    Landscape Theme:
    Butterfly Garden
    Native Garden
    Pollinator Garden
    Winter Garden
    Design Feature:
    Hedge
    Specimen
    Attracts:
    Bees
    Butterflies
    Hummingbirds
    Pollinators
    Small Mammals
    Specialized Bees
    Resistance To Challenges:
    Rabbits
    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