Bottlebrush Buckeye
Aesculus parviflora
Sapindaceae, Hippocastanaceae · broadleaf deciduous shrub · introduced
Last updated
Quick Facts
Height
8–12 ft
Spread
13 ft
Growth Rate
Slow
Light
Full Sun to Shade
Soil
Moist
Water
Moderate
Hardiness
Zones 4a–8b
Bloom Time
June to July
Fall Color
Yellow
Origin
extends from South Carolina, Georgia to Alabama and Florida
Watch for this season
Powdery MildewModerate
Spring Emergence / Primary Infection
Diseases: Regionally Documented (2)
Phenological Calendar
As of May 24, 2026, Puget Sound stations range from 2172.5 to 2394 GDD₃₂. Bottlebrush Buckeye typically reaches 'first bloom' at 3024 GDD₃₂, predicted around Jun 16.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 24, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,394 | Pre-season | 'First bloom' | 630 |
| Kent / Auburn | 2,373 | Pre-season | 'First bloom' | 651 |
| Seattle / UW | 2,332 | Pre-season | 'First bloom' | 692 |
| Olympia / Tumwater | 2,295 | Pre-season | 'First bloom' | 729 |
| Tacoma / Puyallup | 2,259 | Pre-season | 'First bloom' | 765 |
| Bellingham / Whatcom | 2,256 | Pre-season | 'First bloom' | 769 |
| Sequim / Rain Shadow | 2,173 | Pre-season | 'First bloom' | 852 |
View full calendar (2 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ 'First bloom' BBCH '61' NEXT | 3024 | '' est. Jun 16 (avg) |
| 'Full bloom' BBCH '65' | 3330 | '' est. Jun 27 (avg) |
Range: 2515–2896 GDD₃₂
(6yr)
Source: 'Master catalog (OSU, UMD), converted GDD50->GDD32 via Kent bloom-date mapping' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 24, 2026. Predicted dates use 16-day weather forecast through Jun 9, 2026, then climate normals.
Data Maturity Baseline Extension data. Expert review underway.