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Rhododendron macrophyllum (California rhododendron)
Bransford, W.D. Mrs.

Rhododendron macrophyllum D. Don ex G. Don

California rhododendron, California rose-bay, Pacific rhododendron

Ericaceae (Heath Family)

USDA Symbol: RHMA3

USDA Native Status: Native to U.S.

California rhododendron is a 5-25 ft. evergreen shrub with large whorls of leathery, dark-green, oblong leaves setting off spectacular flower clusters. Individual flowers are bell-shaped and range in color from pink to deep rose-purple. When growing in woods, the plants become tree-like to 25 ft. with an attractive, leggy appearance. When open-grown the plant is shorter and more compact. Evergreen shrub with large, deep green, leathery leaves and rounded clusters of large, pink, tubular flowers.

This is the showiest flowering shrub in the forests of western North America, with flower clusters that nearly rival in size and number those of its cultivated relatives. Pacific Rhododendron is confined to drier forest environments in western Washington, where it is the state flower. These same environments, however, are among the moister ones occurring in northern California, at the southern limit of this shrub’s range. The plant is most abundant in Oregon, where mass displays provide a spectacular show in late spring and early summer.

 

From the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Shrub
Size Class: 12-36 ft.
Leaf Color: Dark Green

Bloom Information

Bloom Color: Pink , Purple
Bloom Time: Apr , May , Jun , Jul

Distribution

USA: CA , OR , WA
Canada: BC
Native Distribution: Coastal B.C. & WA, through the Cascades to n. CA; isolated stations on Vancouver Island
Native Habitat: Coastal, montane conifer woods
USDA Native Status: L48(N), CAN(N)

Growing Conditions

Water Use: High
Light Requirement: Part Shade , Shade
Soil Moisture: Moist , Dry
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: None
Soil Description: Moist to drier, well-drained soil.
Conditions Comments: Not Available

Benefit

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

Propagation

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. Propagation is also accompli
Seed Treatment: No pretreatment is necessary.
Commercially Avail: yes
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Mr. Smarty Plants says

Question: We live in Washington State up north by Canadian border. We need a hedge that will survive the constant rain. We have tried cedar. They seem to turn brown and die,one at a time so we keep replacing the dead ones. Need a better solution, the soil has clay a foot or two below surface. We need this for privacy and a little sound barrier wouldn't hurt. Prefer evergreen. Was even told to try bamboo, but its invasive, neighbors are noisy and a pain but wouldn't want to over take both yards with it.
click here to view the full question and answer

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

Recommended Species Lists

Find native plant species by state. Each list contains commercially available species suitable for gardens and planned landscapes. Once you have selected a collection, you can browse the collection or search within it using the combination search.

View Recommended Species page

Additional resources

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

Metadata

Record Modified: 2007-01-01
Research By: TWC Staff

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