Capistrano Rhododendron
Rhododendron 'Capistrano'
Ericaceae · broadleaf evergreen shrub · introduced
Last updated
A dense, mounding evergreen shrub reaching 4 feet in 10 years and 5 to 7 feet at maturity. Frilly, funnel-campanulate flowers are pale greenish-yellow with no markings, carried in dome-shaped trusses of 15 blooms. Midseason flowering. Complex hybrid parentage involving 'Hindustan' and multiple fortunei and catawbiense crosses; bred by David Leach (ARS 972).
Exceptional cold hardiness for a yellow elepidote: rated to -15°F (Zone 5b-8b), making it usable in zones where most yellow rhododendrons fail. Best flower color develops in part shade; full sun positions fade the yellow and can scorch foliage. Acidic, well-drained soil (pH 4.5-6.0). 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 25-May 10 |
| Full bloom BBCH 65 | May 1-May 18 |
| Bloom end BBCH 69 | May 15-Jun 1 |
| Bud set BBCH 55-59 | Jul 15-Sep 15 |