Royal Azalea

Rhododendron schlippenbachii

Ericaceae · broadleaf deciduous shrub · introduced

Last updated May 10, 2026

A deciduous azalea native to Korea and Manchuria, reaching 4 feet. Star-like, delicate flowers, pale to rose pink, 2½ to 3 inches wide, with an inner blotch, borne singly or in loose clusters. Widely considered one of the most beautiful deciduous azalea species.

Full sun on acidic, well-drained soil. Often cited as the finest deciduous azalea species for flower quality and delicacy. Twenty-one diseases and 15 pests documented at the genus level. All parts contain grayanotoxins and are toxic if ingested.

Plant Profile

Size & Form

Height

4 ft

Site Requirements

Light

Full Sun

Soil Drainage

Well Drained

Water

Moderate

Ornamental Interest

Bloom Time

April to May

Origin

Korea and Manchuria

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

Data Maturity

Structured Multiple sources. Expert review underway.