Rhododendron

Rhododendron johnstoneanum

Ericaceae · broadleaf deciduous shrub · introduced

Last updated

A broadleaf shrub in the Ericaceae, R. johnstoneanum is a species from northeastern India and adjacent Myanmar. Blooms on previous season's growth. The species is known for fragrant, white to pale yellow, funnel-shaped flowers sometimes flushed pink or spotted red.

Requires acidic, well-drained soil in sheltered conditions. Best suited to mild climates where winter temperatures do not drop severely. Twenty-one diseases and 15 pests documented at the genus level. All parts are toxic if ingested.

Watch for this season

Root Colonization (Spring–Fall)

Infection at Bud Break

Apothecia Formation & Spore Release

RustHigh

Aecial Stage (Alternate Host)

+ 13 more — see full disease and pest lists below

Diseases: Regionally Documented (21)

Pests: Regionally Documented (15)

Cultivars (1)

'Double Diamond'
Common name: Double Diamond (Johnstone) Rhododendron; Mature height: 4 ft
Hardy to USDA Zone 7
Data Maturity
Structured Multiple sources. Expert review underway.