Torch Azalea
Rhododendron kaempferi
Ericaceae · broadleaf evergreen shrub · introduced
Last updated
A rounded evergreen to semi-deciduous azalea native to Japan (Honshu, Shikoku, Kyushu), reaching 4 to 8 feet tall and 4 to 6 feet wide. Funnel-shaped flowers, typically salmon-red to brick-red, 1 to 2 inches across. Dark green foliage. An important parent in the Kaempferi and Gable hybrid azalea breeding lines.
Hardy in Zone 5a-8b. Part shade on acidic, well-drained soil. Moderate growth rate. A parent species behind many popular evergreen azalea hybrids including the Gable series, contributing color range and cold hardiness. Twenty-one diseases and 15 pests documented at the genus level. All parts contain grayanotoxins and are toxic if ingested.
Quick Facts
Growing Season Stress Expression
Spring Emergence / Primary Infection
Field Observations
Phenological Calendar
| Stage | Typical Window |
|---|---|
| New leaf + flower bud BBCH 11/51 | Mar 15-Apr 15 |
Diseases: Regionally Documented (2)
Cultivars (1)
Evergreen azaleas perform well in Puget Sound Zone 8b with proper siting. Acidic soil is essential; native soils here trend acidic which is favorable. Part shade is ideal; morning sun with afternoon shade reduces lace bug pressure. Good drainage is critical given wet winters; Phytophthora risk in clay soils. Semi-evergreen here; retains most leaves through mild winters, drops more in cold snaps.
— Chris Welch, ISA Certified Arborist