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Torch Azalea Rhododendron kaempferi

Other Common Name(s):

Phonetic Spelling
rho-doh-DEN-dron KAYMP-fer-ee
This plant has high severity poison characteristics.
See below
Description

Torch azalea is a woody, evergreen to semi-evergreen shrub in the Ericaceae (blueberry) family. Found growing in the mountainous regions and grassy hills of Japan.  The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree.  

This erect multistemed shrub has an dense rounded canopy and can grow from 4 to 10 feet tall and 5 to 6 feet wide in about 10 years. Plant in partial to dappled shade with up to 4 hours of sun.  While plants may flower better with more sun, it becomes difficult to maintain their water needs and they can burn.  They need moist well-drained rich acidic soils, avoiding poorly drained soils.  If this is not possible consider planting in a raised bed.  Torch azalea will need some protection from cold so plant it in a sheltered location in the landscape.  Propagate this plant through stem cuttings.

The leaves are evergreen in mild climates and semi-evergreen in areas with cold winters and they provide attractive fall color.  Showy salmon pink to rose red flowers appear late spring to early summer and are one of the few shade flowering evergreen shrubs. 

Low maintenance and easy to grow. This shrub is less demanding than Kurume azaleas (Rhododendron ponticum).  It is the parent plant to many evergreen azaleas.

It works well in a woodland, naturalized area, or Asian garden, planted in a container, window box or near a shaded patio or walkway where the blooms can be enjoyed.  It can be grown as a houseplant.  This plant is often browsed by deer and rabbits, especially new growth, so may need protection. 

Insects, Diseases, and Other Plant Problems:  Rhododendrons are susceptible to insect and disease 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.  Full sun can scorch the leaves and the roots rot if the 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. 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:
  • 'Amoenum'
    Rose purple flowers, 5'-6' tall
  • 'Damio'
    Orange flowers
  • 'Johanna'
    Large red flowers
  • 'Obtusum'
    Small red flowers
'Amoenum', 'Damio', 'Johanna', 'Obtusum'
Tags:
#hummingbirds#evergreen#showy flowers#deciduous#poisonous#semi-evergreen#easy to grow#wildlife plant#nectar plant#low maintenance#spring flowers#specialized bees#deer browsing plant#pollinator plant#Asian garden#flowers late spring#flowers early summer#walkway planting#patio planting#problem for cats#shade flowers#problem for dogs#bee friendly#problem for horses#rabbit browsing plant#woodland garden#container plant
 
Cultivars / Varieties:
  • 'Amoenum'
    Rose purple flowers, 5'-6' tall
  • 'Damio'
    Orange flowers
  • 'Johanna'
    Large red flowers
  • 'Obtusum'
    Small red flowers
'Amoenum', 'Damio', 'Johanna', 'Obtusum'
Tags:
#hummingbirds#evergreen#showy flowers#deciduous#poisonous#semi-evergreen#easy to grow#wildlife plant#nectar plant#low maintenance#spring flowers#specialized bees#deer browsing plant#pollinator plant#Asian garden#flowers late spring#flowers early summer#walkway planting#patio planting#problem for cats#shade flowers#problem for dogs#bee friendly#problem for horses#rabbit browsing plant#woodland garden#container plant
  • Attributes:
    Genus:
    Rhododendron
    Species:
    kaempferi
    Family:
    Ericaceae
    Life Cycle:
    Woody
    Recommended Propagation Strategy:
    Stem Cutting
    Country Or Region Of Origin:
    Japan
    Wildlife Value:
    Nectar from flowers attracts hummingbirds and bees. Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli.
    Dimensions:
    Height: 4 ft. 0 in. - 10 ft. 0 in.
    Width: 5 ft. 0 in. - 6 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Poisonous
    Shrub
    Woody Plant Leaf Characteristics:
    Semi-evergreen
    Habit/Form:
    Dense
    Erect
    Multi-stemmed
    Rounded
    Maintenance:
    Low
    Texture:
    Medium
  • Cultural Conditions:
    Light:
    Dappled Sunlight (Shade through upper canopy all 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
    Available Space To Plant:
    3 feet-6 feet
    6-feet-12 feet
    NC Region:
    Coastal
    Piedmont
    USDA Plant Hardiness Zone:
    5b, 5a, 6b, 6a, 7b, 7a
  • Fruit:
    Fruit Type:
    Capsule
  • Flowers:
    Flower Color:
    Gold/Yellow
    Orange
    Pink
    Red/Burgundy
    White
    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:
    2 to 3 flowers in a terminal raceme Salmon-red, orange-red, pink to rosy scarlet and white 5 petaled 1 1/2'"-2" across funnel shaped flowers appear late spring to early summer.
  • Leaves:
    Woody Plant Leaf Characteristics:
    Semi-evergreen
    Leaf Color:
    Gold/Yellow
    Green
    Leaf Feel:
    Glossy
    Deciduous Leaf Fall Color:
    Red/Burgundy
    Leaf Type:
    Simple
    Leaf Arrangement:
    Alternate
    Leaf Shape:
    Elliptical
    Lanceolate
    Leaf Margin:
    Entire
    Hairs Present:
    Yes
    Leaf Length:
    1-3 inches
    Leaf Width:
    1-3 inches
    Leaf Description:
    Simple, alternate, glossy dark green above lighter below lanceolate to elliptic leaves 2" long 1 1/8" wide with smooth margins; reddish fall color. Spring leaves are decidious, summer leaves are evergreen or deciduous depending on winter temperatures. Petioles have dense brown hairs, as do both sides of the leaf especially at the midrid.
  • Stem:
    Stem Is Aromatic:
    No
    Stem Surface:
    Hairy (pubescent)
    Stem Description:
    Dense flattend forward pointing red-brown hairs.
  • Landscape:
    Landscape Location:
    Container
    Naturalized Area
    Patio
    Walkways
    Woodland
    Landscape Theme:
    Asian Garden
    Design Feature:
    Mass Planting
    Small groups
    Attracts:
    Hummingbirds
    Pollinators
    Specialized Bees
    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
    Sap/Juice
    Seeds
    Stems