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Rhododendron calendulaceum

Common Name(s):

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

Rhododendron calendulaceum, commonly known as flame azalea, is an upright, loosely branched deciduous shrub that typically matures to 4-8' (infrequently to 10-15’) tall and to 8-10’ wide. It is native primarily to woodland slopes and mountain balds in the Appalachian Mountains from Pennsylvania to Georgia.

It needs a few hours of direct sun.  It is a slow plant to become established.  It is loosely branched plant with an upright habit.  It's excellent for naturalistic landscape.

This species is an important parent of many deciduous azalea hybrids.

The common name of flame azalea is in reference to the purported resemblance of the upright flower buds to candle flames.

The bath is thin and gray-brown with a finely shredded appearance.

Fire Risk: This plant has a medium flammability rating. 

Regions:  Mountain

Seasons of Interest: 

  Blooms:   Spring, summer           Nut/Fruit/Seed:  Late summer

Insects, Diseases, and Other Plant Problems:  Rhododendrons are susceptible to insect and disease problems.  Insect problems include aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly.  Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew.  Full sun can scorch the leaves and the roots rot if soil does not drain well.   A healthy plant in the right place with proper maintenance should have few problems. This plant is frequently damaged by deer.

 

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:
#bumble bees#hummingbirds#deciduous#fall color#drought tolerant#wildlife plant#showy#nectar plant#native shrub#native bees#rabbit resistant#hedges#specialized bees#fire#medium flammability#NC native#native garden#pollinator plant#larval host plant#food source summer#food source herbage#food source nectar#food source pollen#nectar plant late spring#mammals#butterfly friendly#nectar plant early summer#nectar plant mid-summer#problem for cats#pollinator garden#problem for dogs#problem for horses#audubon
 
Cultivars / Varieties:
  • 'Chatooga'
  • 'Cherokee'
  • 'Flame Azalea'
  • 'Richard Beilski'
'Chatooga', 'Cherokee', 'Flame Azalea', 'Richard Beilski'
Tags:
#bumble bees#hummingbirds#deciduous#fall color#drought tolerant#wildlife plant#showy#nectar plant#native shrub#native bees#rabbit resistant#hedges#specialized bees#fire#medium flammability#NC native#native garden#pollinator plant#larval host plant#food source summer#food source herbage#food source nectar#food source pollen#nectar plant late spring#mammals#butterfly friendly#nectar plant early summer#nectar plant mid-summer#problem for cats#pollinator garden#problem for dogs#problem for horses#audubon
  • Attributes:
    Genus:
    Rhododendron
    Species:
    calendulaceum
    Family:
    Ericaceae
    Life Cycle:
    Woody
    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
  • 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:
    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:
    Display/Harvest Time:
    Summer
    Fruit Type:
    Capsule
    Fruit Description:
    Displays from June to September.
  • Flowers:
    Flower Color:
    Gold/Yellow
    Orange
    Pink
    Red/Burgundy
    Flower Value To Gardener:
    Showy
    Flower Bloom Time:
    Spring
    Summer
    Flower Shape:
    Funnel
    Flower Size:
    1-3 inches
    Flower Description:
    The Flame azalea has 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 Margin:
    Entire
    Serrate
    Hairs Present:
    No
    Leaf Description:
    The leaves of the Flame azalea are 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:
    Houseplants
    Naturalized Area
    Woodland
    Landscape Theme:
    Butterfly Garden
    Pollinator Garden
    Design Feature:
    Hedge
    Attracts:
    Bees
    Butterflies
    Hummingbirds
    Pollinators
    Small Mammals
    Specialized Bees
    Resistance To Challenges:
    Rabbits
    Problems:
    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