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Rhododendron occidentale (Western azalea)
Sherman, Doug

Rhododendron occidentale

Rhododendron occidentale (Torr. & A. Gray) A. Gray

Western Azalea

Ericaceae (Heath Family)



USDA Native Status: L48 (N)

A fragrant, loosely branched, spreading shrub that can reach 30 ft. in height but is usually 3-9 ft. tall. The bark is shredding. The leaves are thin, light green and oval. White, tubular flowers may be tinged pink and have a yellow-blotched upper lobe. Flowers occur in tightly compact clusters. A shrub with large, white to deep pink, very fragrant flowers in large clusters at stem ends.

Flower variations include mixtures of pale pink, deep pink, and yellow-orange. An evergreen, pink-flowered relative, California Rosebay (R. macrophyllum), grows from British Columbia to California and makes a choice ornamental; it is the state flower of Washington, where it is known as Red Rhododendron.


From the Image Gallery

1 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Shrub
Leaf Retention: Deciduous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Breeding System: Flowers Bisexual
Fruit Type: Capsule
Size Notes: Up to about 30 feet tall, usually much shorter.
Leaf: Green

Bloom Information

Bloom Color: White , Pink , Orange , Yellow
Bloom Time: Mar , Apr , May , Jun , Jul , Aug


Native Distribution: CA mts. from Kern & Santa Cruz Cos., n. to s.w. OR
Native Habitat: Stream banks and other moist places below 7500 ft.

Growing Conditions

Water Use: High
Light Requirement: Part Shade
Soil Moisture: Moist
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: None
Soil Description: Moist, well-drained soil.
Conditions Comments: A parent of many hybrid azaleas.


Warning: Rhododendrons contain poisonous substances and should not be ingested by humans or animals. Honey made from flowers also may be toxic. POISONOUS PARTS: All parts. Highly Toxic, May be Fatal if eaten. Symptoms include salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, difficult breathing, progressive paralysis of arms and legs, coma. Toxic Principle: Andromedotoxin. (Poisonous Plants of N.C.)
Conspicuous Flowers: yes

Value to Beneficial Insects

Special Value to Bumble Bees

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.

Butterflies and Moths of North America (BAMONA)

Hoary Comma
(Polygonia gracilis)

Adult Food Source
Learn more at BAMONA


Description: Combine seeds loosely with sphagnum moss and sprinkle lightly over a 2:1 perlite/peat mixture. Optimum temperatures for germination are 45-50 degrees. Transplant seedlings to acid soil with a high content of organic matter. Cultivated evergreen azaleas
Seed Treatment: No pretreatment is necessary.
Commercially Avail: yes

National Wetland Indicator Status

Status: FAC FAC
This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Santa Barbara Botanic Garden - Santa Barbara, CA


Bibref 1186 - Field Guide to Moths of Eastern North America (2005) Covell, C.V., Jr.
Bibref 1185 - Field Guide to Western Butterflies (Peterson Field Guides) (1999) Opler, P.A. and A.B. Wright

Search More Titles in Bibliography

Web Reference

Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Rhododendron occidentale in USDA Plants
FNA: Find Rhododendron occidentale in the Flora of North America (if available)
Google: Search Google for Rhododendron occidentale


Record Modified: 2023-04-03
Research By: TWC Staff

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