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Pacific Rhododendron
Rhododendron macrophyllum

About Pacific Rhododendron (Rhododendron macrophyllum) Pacific Rhododendron, Coast Rhododendron or Big Leaf Rhododendron is a broadleaf evergreen Rhododendron species native to western North America. Pacific rhododendron is found along the Pacific Coast from British Columbia to Monterey County in California. It is widely distributed in the Coast and Cascade Mountain Ranges. Pacific rhododendron is less abundant in the Coastal Mountains of Washington and northern Oregon and more common south of the Siuslaw River.
Plant Description
Plant Type

Max. Height
10 - 15 ft (3 - 4.6 m)


Growth Rate


Flower Color
Purple, Pink

Flowering Season

Native Status

Natural Setting
Site Type
Moist places

Part Shade

Elevation ?
9' - 6298'

Annual Precip. ?
16.2" - 147.0"

Summer Precip. ?
0.23" - 5.33"

Coldest Month ?
37.3° F - 50.5° F

Hottest Month ?
55.9° F - 72.5° F

Humidity ?
0.01 vpd - 19.12 vpd

Soil Description
Prefers loamy or clay soils. Grows poorly in sandy soils.

Sunset Zones ?
4*, 5*, 6*, 7, 14, 15, 16, 17

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

Propagation ?
For propagating by seed: No treatment. Best sown on milled sphagnum moss.

Common uses
Deer Resistant

Nursery Availability
Sometimes Available

Other Names
Common Names
California Rosebay, Coast Rhododendron

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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