Catawba Rhododendron

'Full bloom'

Rhododendron catawbiense

Ericaceae · broadleaf evergreen shrub · introduced

Last updated May 10, 2026

A broadleaf evergreen shrub reaching 6 ft tall and 8 to 10 ft wide, native to the Allegheny Mountains of the eastern United States. Named after the Catawba River in North Carolina. One of the most cold-hardy elepidote species, tolerating temperatures to -25F. Leaves are medium-sized, oval to oblong, smooth and shiny dark green above, cupped in shape.

Part shade on acidic, well-drained to adaptable soil. Low to moderate water needs. One of the most important parent species in rhododendron hybridizing, contributing extreme cold hardiness and dense habit to countless cultivars. Twenty-one diseases and 15 pests documented at the genus level.

Plant Profile

Size & Form

Height

6 ft

Spread

8-10 ft

Site Requirements

Light

Part Shade

Soil Drainage

Well Drained, Adaptable

Soil pH

acidic

Water

Low to moderate

Hardiness

Zones –25F

Ornamental Interest

Bloom Time

April to June

Fall Color

Yellow

Origin

eastern US (Allegheny Mountains), named after the Catawba

Cylindrocladium Blight and Root RotHigh

Root Colonization (Spring–Fall)

Leaf and Flower GallHigh

Gall Development & Sporulation

Powdery MildewHigh

Active Conidial Spread

RustHigh

Uredinial Stage (Summer)

+ 13 more — see full disease and pest lists below

Diseases: Regionally Documented (21)

Root Rot (Phytophthora spp.) Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Ovulinia azaleae Ovulinia Petal Blight Lime-induced Chlorosis Symptom category — not a single disease Leaf Spot Exobasidium vaccinii Leaf and Flower Gall Cylindrocladium scoparium Cylindrocladium Blight and Root Rot Botrytis Petal Blight Multiple soilborne and waterborne pathogens cause cutting... Cutting Rots Leaf Burn Ramorum Blight (Sudden Oak Death) Botryosphaeria dothidea Botryosphaeria Dieback Seifertia azaleae Bud Blight Rhododendron necrotic ringspot virus Necrotic Ringspot Multiple genera (Melampsoridium, Thekopsora, Naohidemyces... Rust Taphrina wiesneri Witches' Broom Armillaria spp. — primarily A Armillaria Root Rot Pestalotiopsis sydowiana Gray Blight Physiological leaf spot Phytophthora Blight Tylenchorhynchus claytoni Nematode, Stunt

Pests: Regionally Documented (15)

Tetranychidae Spider mite Otiorhynchus spp. Root weevil Choristoneura rosaceana Obliquebanded Leafroller Caloptilia azaleella Azalea leafminer Stephanitis pyrioides Azalea Lace Bug Acanthococcus azaleae Azalea bark scale Aphidoidea Aphid Lepidoptera Caterpillars Parthenolecanium spp. Lecanium scale Stephanitis rhododendri Rhododendron lace bug Dialeurodes chittendeni Rhododendron whitefly Nematus lipovskyi Azalea sawfly Cacoecimorpha pronubana Carnation tortrix Icerya purchasi Cottony cushion scale Coleotechnites huntella Rhododendron bud moth

Phenological Calendar

As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Catawba Rhododendron has passed 'full bloom' (1580 GDD₃₂).

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026

Station	GDD₃₂	Current Stage	Next	To Go
Issaquah / East King	2,673	'Full bloom'	—	—
Kent / Auburn	2,665	'Full bloom'	—	—
Seattle / UW	2,610	'Full bloom'	—	—
Olympia / Tumwater	2,570	'Full bloom'	—	—
Tacoma / Puyallup	2,535	'Full bloom'	—	—
Bellingham / Whatcom	2,533	'Full bloom'	—	—
Sequim / Rain Shadow	2,436	'Full bloom'	—	—

View full calendar (2 stages)

Stage	GDD₃₂	Typical Window	What to Look For
'First bloom' BBCH '61'	1325	''	''
● 'Full bloom' BBCH '65' NOW	1580	''	''

Regional estimate

Range: 971–1192 GDD₃₂ (6yr)

Source: 'Master catalog (OSU), converted GDD50->GDD32 via Kent bloom-date mapping' About GDD₃₂ →

Season tracker for Kent / Auburn as of Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.

Cultivars (2)

'Boursault'

Common name: Catawbiense Boursault Rhododendron; Mature height: 6 ft

'The General'

Data Maturity

Structured Multiple sources. Expert review underway.