Koreanspice Viburnum
Viburnum carlesii
Adoxaceae, Caprifoliaceae · broadleaf deciduous shrub · introduced
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Koreanspice viburnum is a deciduous broadleaf shrub from Korea reaching 4-8 ft. It produces fragrant flowers (10-14 mm) that are pink in bud, opening white, in hemispherical clusters about 6 cm wide. Bloom time is March to April.
Koreanspice viburnum is hardy in zones 4-8 and prefers full sun to part shade. Prune immediately after flowering through early summer since flowers form on old wood. It tolerates black walnut and attracts birds with minimal maintenance.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Koreanspice Viburnum has passed beginning of flowering (876 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 23, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,593 | Beginning of flowering | — | — |
| Seattle / UW | 1,554 | Beginning of flowering | — | — |
| Kent / Auburn | 1,537 | Beginning of flowering | — | — |
| Olympia / Tumwater | 1,505 | Beginning of flowering | — | — |
| Bellingham / Whatcom | 1,483 | Beginning of flowering | — | — |
| Tacoma / Puyallup | 1,472 | Beginning of flowering | — | — |
| Sequim / Rain Shadow | 1,434 | Beginning of flowering | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● Beginning of flowering BBCH 61 NOW | 876 | — |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? Source GDD₅₀ thresholds from Herms 2004 (OSU, Secrest Arboretum, Ohio) and UMD IPMnet (Gill & Klick, mid-Atlantic), converted to GDD₃₂ via Kent bloom-date mapping. Season tracker for Kent / Auburn as of Apr 23, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.