Jean Marie Rhododendron
Rhododendron 'The Honourable Jean Marie de Montague'
Ericaceae · broadleaf evergreen shrub · introduced
Last updated
A dense, mounded evergreen shrub reaching 5 feet in 10 years and 6 to 8 feet at maturity. Broadly funnel-campanulate flowers, 3⅛ inches wide, strong red with dark red spotting in the dorsal throat, carried in dome-shaped trusses of 10 to 14 blooms. Midseason flowering. A hybrid of R. griffithianum crossed with an unknown parent, bred by van Nes & Sons in the Netherlands (RHS 58).
The benchmark red elepidote rhododendron: the vivid, heavy-substanced red flower against which other red hybrids are compared. Thrives in heat and sun. Hardy to -5°F (Zone 7a-9a). Full sun to part shade on acidic, well-drained soil (pH 4.5-6.0). Consistent, reliable annual bloom. Cold hardiness is not as deep as the ironclad catawbiense hybrids; not suitable for extreme cold zones. Twenty-one diseases and 15 pests documented at the genus level. All parts contain grayanotoxins and are toxic if ingested.
Quick Facts
Root Colonization (Spring–Fall)
Infection at Bud Break
Apothecia Formation & Spore Release
Aecial Stage (Alternate Host)
+ 13 more — see full disease and pest lists below
Phenological Calendar
| Stage | Typical Window |
|---|---|
| Bud swell BBCH 01-03 | Mar 15-Apr 15 |
| Bloom start BBCH 61 | Apr 15-May 1 |
| Full bloom BBCH 65 | Apr 25-May 10 |
| Bloom end BBCH 69 | May 5-May 25 |
| Bud set BBCH 55-59 | Jul 15-Sep 15 |