Flower profile

Pacific rhododendron

Rhododendron macrophyllum

Pacific rhododendron (Rhododendron macrophyllum) is a shrub or small tree in the Ericaceae family, native in the lower 48 states, blooming mostly May–July across the U.S.

★ Official state flower of Washington (1949)Native in the lower 48

Pacific rhododendron is a flowering plant that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 2 states, and across the U.S. it's most often seen in bloom in May–July.

3states where USDA records it

2Bloomipedia state lists include it

6,277U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Oregon, Washington

🏅

Washington's official state flower since 1949. Visit the Washington page → ^{RCW 1.20.030}

Quick look

Rhododendron macrophyllum, also known as the Pacific rhododendron, California rose bay, California rhododendron, coast rhododendron or big leaf rhododendron, is a large-leaved species of Rhododendron native to the Pacific Coast of North America. It is the state flower of Washington.
From Wikipedia's article Rhododendron macrophyllum, CC BY-SA 4.0.

It belongs to the Ericaceae family. ^iNaturalist
USDA PLANTS describes it as a shrub / a tree with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 3 states. ^{USDA PLANTS}
NatureServe lists it as native to Oregon and Washington. ^NatureServe
In Oregon, most iNaturalist sightings of it in flower come in May–July. ^iNaturalist
In Washington, most iNaturalist sightings of it in flower come in May–June. ^iNaturalist
USDA PLANTS lists its flower color as purple. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as spring. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 15 ft. ^{USDA PLANTS}
iNaturalist has 3,013 research-grade sightings of it in Oregon, ranking #52 among the 184 flowers on our Oregon list. ^iNaturalist
iNaturalist has 1,209 research-grade sightings of it in Washington, ranking #103 among the 187 flowers on our Washington list. ^iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (1,137 records)

Bloom time in the 2 states whose Bloomipedia list includes it

State	Type	Peak bloom	Sightings*
Oregon	Native	May–July	3,013
Washington	Native	May–June	1,209

Conservation status

Federal (U.S. ESA): Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. ^{USFWS ECOS}
NatureServe global: G5 Secure worldwide. ^NatureServe
Oregon: Not listed Not on Oregon endangered and threatened plants (OAR 603-073-0070). NatureServe: S5, secure in Oregon. ^{OAR 603-073-0070}
Washington: No list Washington has no state law listing endangered or threatened plants (the Washington Natural Heritage Program's rare plant list isn't regulatory), so we show NatureServe's Washington ranks instead. NatureServe: SNR, not yet ranked in Washington.
Rare elsewhere: No other U.S. state ranks it S1, S2, SH or SX.

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleToxic (moderate, per USDA)

USDA PLANTS rates its toxicity as “moderate.” (USDA's rating covers people and livestock and doesn't say which parts.) NC State Extension has no page for it. ^{USDA PLANTS}

For petsToxic to dogs, cats and horses

ASPCA's entry “Azalea” (Rhododendron spp), which covers the whole genus, lists it as toxic to dogs, cats and horses. Signs include: Vomiting (not in horses), diarrhea, weakness, cardiac… ^ASPCA

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records Pacific rhododendron in 3 states.

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recorded by USDA PLANTS on our state lists not recorded

See the full list of states

California, Oregon, Washington.

Oregon counties with USDA records: Benton, Clackamas, Coos, Curry, Deschutes, Douglas, Hood River, Jackson, Jefferson, Josephine, Klamath, Lane, Lincoln, Linn, Marion, Multnomah, Polk, Tillamook, Washington, Yamhill.

Washington counties with USDA records: Clallam, Clark, Island, Jefferson, King, Kitsap, Lewis, Mason, Pierce, Skagit, Skamania.

Growing conditions

USDA PLANTS gives Pacific rhododendron a medium shade tolerance, none drought tolerance and high moisture use. It is rated for soil pH 5.5 to 7.0 and winter lows down to 7 °F.

Shade tolerance: Medium
Drought tolerance: None
Moisture use: High
Soil textures it is adapted to: medium, fine
Soil pH range: 5.5 to 7.0
Minimum temperature tolerated: 7 °F
Frost-free days needed (minimum): 270
Annual precipitation range: 55 to 125 inches
Minimum root depth: 12 inches
Salinity tolerance: None
Fertility requirement: Medium
Growth rate: Moderate
Lifespan: Moderate
Active growth period: Spring and Summer
Fruit or seed: Black · Summer to Fall
Can be propagated by: bare root, container, cuttings, seed
Commercial availability: Routinely Available

From the USDA PLANTS characteristics data for RHMA3. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Native; Lower 48 states: Native.

Other scientific names (synonyms in USDA PLANTS): Rhododendron californicum.

County records: USDA PLANTS lists it in 40 counties across 3 states; the most are in Oregon (20), Washington (11), California (9).

Other Rhododendron on Bloomipedia (11): Rhododendrons and azaleas, Great rhododendron, Labrador tea, Pinxter flower, Flame azalea, Mock azalea, Rhodora, Mountain azalea, Swamp azalea, Catawba rhododendron.

More from the Ericaceae family (55 on Bloomipedia; most observed first): Ghost pipe, Striped wintergreen, Mountain laurel, Eastern teaberry (wintergreen), Salal, Woodland pinedrops, Pinesap, Trailing arbutus (mayflower).

More Oregon flowers

Salal

Gaultheria shallon

Native

🌼 Blooms in OR: May–July

Woodland pinedrops

Pterospora andromedea

Native

🌼 Blooms in OR: July–August

Ghost pipe

Monotropa uniflora

Native

🌼 Blooms in OR: June–August

Sources

USDA, NRCS. PLANTS Database, profile RHMA3.
iNaturalist, Rhododendron macrophyllum: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Rhododendron macrophyllum (lead quoted under CC BY-SA 4.0).
RCW 1.20.030: Washington state flower.
Oregon: Oregon endangered and threatened plants (OAR 603-073-0070).
Oregon: Oregon noxious weed quarantine, A and B weeds (OAR 603-052-1200).
Washington: Washington State noxious weed list (WAC 16-750-005, -011, -015).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Rhododendron macrophyllum (global and state ranks).
Edibility and toxicity: USDA PLANTS; ASPCA.
Photo: Miguel Vieira via iNaturalist · CC BY 4.0 · resized.