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Western Azalea
Rhododendron occidentale
About Western Azalea (Rhododendron occidentale) Nurseries Show All Photos Western Azalea is best known of three Rhododendron species native to California. It occurs as far north as Bandon, Oregon and as far south as the Palomar Mountain area in southern California, possibly also in Baja California, Mexico. It is a shrub capable of growing to 5 meters tall but more commonly around 3 meters. The leaves are deciduous, 3-9 centimeters long and 1-3 centimeters broad. The flowers are 3.5-5 centimeters in diameter, with five lobes on the corolla; color varies from white to pink, often with a yellow blotch. It is most often found in moist forested areas. It typically gets summer fog drip or some other source of summer moisture. It is deciduous and will be leafless for some months out of the year, but does produce interesting fall color. It needs some sun for good flower production but also likes some high shade such as the edge of a woodland.
Plant Description
Plant Type

Max. Height
6 - 16.4 ft (1.8 - 5 m)

Max. Width
10 ft (3.0 m)

Upright, Rounded

Fragrant - Pleasant

Growth Rate

Winter Deciduous

Flower Color
White, Pink

Flowering Season

Native Status

Natural Setting
Site Type
Streambanks, seeps, wet meadows or other moist areas within or adjacent to forest or woodlands, typically in mountainous areas

Part Shade

Elevation ?
-111' - 10286'

Annual Precip. ?
5.2" - 151.6"

Summer Precip. ?
0.18" - 5.67"

Coldest Month ?
25.1° F - 58.3° F

Hottest Month ?
47.2° F - 87.0° F

Humidity ?
0.01 vpd - 37.61 vpd

Soil Description
Prefers deep woodland soil with high organic content, can be acidic such as peat or pine needles

Soil PH
4.0 - 8.0

Soil Toxicity Tolerance
Tolerates Sodic Soil


Cold Tolerance(° F)
Tolerates cold to -10° F

Sunset Zones ?
3, 4*, 5*, 6*, 7*, 14*, 15*, 16*, 17*, 19, 20, 21, 22, 23, 24

Companion Plants
Landscaping Information
Water Requirement ?
Moderate - High
Extremely Low
Very Low
Moderate - High

Moderately Popular

Max. Summer Water ?
1/week, Keep moist
No Summer Water
Keep moist

Deep Organic

Some occasional thinning of branches may be needed to keep an attractive, open structure. Prune in winter when the plant is dormant

Propagation ?
Seeds, cuttings or layering.  For propagating by seed: No treatment. Best sown on milled sphagnum moss.

Common uses
Butterfly Gardens

Nursery Availability
Sometimes Available

Other Names
Botanical Names
Rhododendron occidentale var. occidentale

Common Names
Sonoma Azalea

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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