Japanese Stewartia
Stewartia pseudocamellia
Theaceae · broadleaf deciduous tree · introduced
Last updated
Japanese stewartia is a deciduous tree native to Japan, reaching 30-50 feet tall with exfoliating, mottled gray and tan bark. The tree produces white flowers with crinkled petals and orange stamens in midsummer and oblong leaves that turn striking purple-red to orange in fall.
Japanese stewartia thrives in partial shade to full sun with well-drained, acidic, humus-rich soil and consistent moisture. Hardy to zones 5-8, it is slow to medium in growth rate with exceptional ornamental value from flowers, fall foliage, and winter bark. The tree does not tolerate drought stress.
Quick Facts
Field Observations
Phenological Calendar
As of May 18, 2026, Puget Sound stations range from 2022.7 to 2224.5 GDD₃₂. Japanese Stewartia typically reaches 'first bloom' at 2878 GDD₃₂, predicted around Jun 9.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 18, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,225 | Pre-season | 'First bloom' | 654 |
| Kent / Auburn | 2,194 | Pre-season | 'First bloom' | 684 |
| Seattle / UW | 2,164 | Pre-season | 'First bloom' | 714 |
| Olympia / Tumwater | 2,128 | Pre-season | 'First bloom' | 750 |
| Bellingham / Whatcom | 2,098 | Pre-season | 'First bloom' | 780 |
| Tacoma / Puyallup | 2,092 | Pre-season | 'First bloom' | 786 |
| Sequim / Rain Shadow | 2,023 | Pre-season | 'First bloom' | 855 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Flower bud formation' BBCH '55' | — | 'Mid-May' |
| ○ 'First bloom' BBCH '61' NEXT | 2878 | '' est. Jun 9 (avg) |
| 'Full bloom' BBCH '65' | 3498 | '' est. Jun 30 (avg) |
Source: 'Master catalog (UMD), converted GDD50->GDD32 via Kent bloom-date mapping' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 18, 2026. Predicted dates use 16-day weather forecast through Jun 3, 2026, then climate normals.