Sweet Mockorange
Philadelphus coronarius
Hydrangeaceae · [VERIFY] · introduced
Last updated
Philadelphus coronarius (Hydrangeaceae) is a deciduous shrub native to southeastern Europe and western Asia. It grows 6 to 10 feet tall with an upright, arching habit. In late spring, clusters of intensely fragrant white flowers (about 1 inch across) cover the plant. The fragrance is considered among the finest of any temperate shrub.
Sweet mockorange grows in full sun to part shade on a range of well-drained soils. It blooms on old wood, so pruning should follow flowering. The species is vigorous and may become leggy without periodic renewal pruning (removing oldest canes at ground level). No serious pest or disease problems are typical.
Quick Facts
Phenological Calendar
As of April 19, 2026, Puget Sound stations range from 1342.9 to 1500.8 GDD₃₂. Sweet Mockorange typically reaches beginning of flowering at 1832 GDD₃₂, predicted around May 5.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 19, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,501 | Pre-season | Beginning of flowering | 331 |
| Seattle / UW | 1,465 | Pre-season | Beginning of flowering | 367 |
| Kent / Auburn | 1,441 | Pre-season | Beginning of flowering | 391 |
| Olympia / Tumwater | 1,415 | Pre-season | Beginning of flowering | 417 |
| Bellingham / Whatcom | 1,390 | Pre-season | Beginning of flowering | 442 |
| Tacoma / Puyallup | 1,381 | Pre-season | Beginning of flowering | 452 |
| Sequim / Rain Shadow | 1,343 | Pre-season | Beginning of flowering | 489 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Beginning of flowering BBCH 61 NEXT | 1832 | — est. May 5 (forecast) |
| Full bloom BBCH 65 | 2438 | — est. May 31 (avg) |
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 19, 2026. Predicted dates use 16-day weather forecast through May 5, 2026, then climate normals.