Bottlebrush Buckeye
Aesculus parviflora
Sapindaceae, Hippocastanaceae · broadleaf deciduous shrub · native
Last updated
This profile contains verified botanical data. Regional field notes and expert review are in progress.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Bottlebrush Buckeye typically reaches 'first bloom' at 3024 GDD₃₂, predicted around Jun 23.
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 | Pre-season | 'First bloom' | 1,431 |
| Seattle / UW | 1,554 | Pre-season | 'First bloom' | 1,470 |
| Kent / Auburn | 1,537 | Pre-season | 'First bloom' | 1,487 |
| Olympia / Tumwater | 1,505 | Pre-season | 'First bloom' | 1,520 |
| Bellingham / Whatcom | 1,483 | Pre-season | 'First bloom' | 1,541 |
| Tacoma / Puyallup | 1,472 | Pre-season | 'First bloom' | 1,552 |
| Sequim / Rain Shadow | 1,434 | Pre-season | 'First bloom' | 1,590 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ 'First bloom' BBCH '61' NEXT | 3024 | '' est. Jun 23 (avg) |
| 'Full bloom' BBCH '65' | 3330 | '' est. Jul 3 (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 23, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.