wetland shrub

Western azalea

Rhododendron occidentale

Native to California and Oregon

California mountains from Kern and Santa Cruz counties, north to southwestern Oregon

Light Partial shade Sun tolerance
Moisture Moist Moisture preference
Zones 6–10 Cold to heat range
Bloom Apr–Jul Flowering time
Height up to 30 ft to 9.1 m
Life cycle Perennial Annual to perennial

In the garden

A wetland shrub for partial shade and evenly moist soil. Its white flowers peak in June. At up to 30 ft, it needs room in rain gardens, pond edges, and damp low spots. Hardy in USDA zones 6–10.

Growing conditions

Light

Full sun Partial shade Full shade

Moisture

Dry Moist Wet

Hardiness zones

Find your zone:

When it blooms

The Western azalea's white flowers bloom April to July, peaking in June. This early-summer display draws bees and butterflies.

Western azalea blooms white, pink, orange & yellowFoliage

Pollinators & wildlife

Bees Yellow-faced Bumble Bee

also Black-tailed Bumble Bee, Fuzzy-Horned Bumble Bee, Sitka Bumble Bee +1 more
Buff-tailed Bumble Bee
Butterflies Monarch also Western Tiger Swallowtail, Pale Swallowtail

Butterflies that use this plant

Documented host and nectar records. Each links to a planting guide for that butterfly.

Full plant details

Where it grows

Habitat: WetlandThe wild plant community it grows in.
Native range: California and OregonUnited States (2): CA, OR. Where it grows wild on its own, by state and province.
Native distribution: California mountains from Kern and Santa Cruz counties, north to southwestern OregonThe same native range, usually more exact than the state list, and often noting where it has spread beyond it.

Growing conditions

Light: Partial shadeHow much sun it takes, from full sun to full shade.
Moisture: MoistThe soil dampness it prefers, from dry to wet.
Hardiness zones: USDA 6–10 · Canadian 8–9The cold-to-heat climate range it survives.
Soil: Moist, well-drained soilThe soils it grows in naturally.
Soil pH: 4.5–6.5The acidity to alkalinity it tolerates (7 is neutral).
Soil quality: MediumHow rich a soil it needs. Many natives prefer lean soil and flop in rich beds.
Water use: HighHow thirsty it is, a rough guide to how often to water.
Salinity tolerance: NoneHow well it copes with salty soil, near roads or the coast.
Lime (CaCO₃) tolerance: NoneHow well it copes with chalky, lime-rich soil.

Growth & form

Height: up to 30 ft (to 9.1 m)Typical mature height.
Life cycle: PerennialWhether it lives a single season (annual), two (biennial), or returns for years (perennial).
Growth rate: ModerateA relative ranking versus other plants of the same type (USDA), not an absolute rate.
Shape: ErectIts overall silhouette.
Root depth: 12+ in (30+ cm)How far the roots reach, a guide to drought resilience and transplanting.

Flowers, foliage & fruit

Type: ShrubWhat kind of plant it is.
Bloom: Apr–JulWhen it flowers.
Flower color: White, Pink, Orange, YellowThe bloom color, or colors.
Fruit/Seeds: ripens Jun–OctThe seed or fruit it sets after flowering.
Toxicity: Poisonous if eatenWhether any part is poisonous to people or pets.

Propagation & seed

Cold stratification: Not requiredWhether seed needs a cold, moist spell before it will germinate.
Propagation: Bare root, container, cuttings, seedHow to start new plants.
Seed: ~4 million seeds per poundNotes on the seed and how to sow it.
Seed spread rate: RapidHow readily it self-sows. Slow or none means well-behaved, not a spreader.
Seedling vigor: MediumHow strongly young seedlings establish.
Vegetative spread: NoneWhether it creeps outward or stays put in a clump.