Cilpinense Rhododendron
Rhododendron 'Cilpinense'
Ericaceae · broadleaf evergreen shrub · introduced
Last updated
A rounded, open evergreen shrub reaching 3 feet in 10 years and 4 to 5 feet at maturity. Funnel-shaped pale pink flowers shaded darker pink, 3 inches wide, in small trusses of 2 to 3 blooms. One of the earliest-blooming garden rhododendron hybrids, flowering in February to March. A hybrid of R. ciliatum crossed with R. moupinense, bred by Lord Aberconway at Bodnant Garden, Wales (RHS 58).
The extreme early bloom is both the selling point and the risk: flowers open weeks before most rhododendrons and are vulnerable to late freezes. Hardy to 5°F (Zone 7b-9a). Part shade to full sun on acidic, well-drained soil (pH 4.5-6.0). Sheltered positions near buildings or walls improve flower survival in cold snaps. 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 | Feb 25-Mar 20 |
| Full bloom BBCH 65 | Mar 5-Apr 1 |
| Bloom end BBCH 69 | Mar 20-Apr 15 |
| Bud set BBCH 55-59 | Jul 15-Sep 15 |