Silk Tree
Albizia julibrissin
Fabaceae · broadleaf deciduous tree · introduced
Last updated
Plant Profile
Size & Form
Height
20–30 ft
Spread
32 ft
Growth Rate
Fast
Size at 20 yr
20 ft
Lifespan
Short-lived
Site Requirements
Light
Full Sun
Soil Drainage
Wet Tolerant
Soil pH
4.8-7.3
Water
Moderate
Drought Tolerance
Medium
Hardiness
Zones 6a–8b
Ornamental Interest
Bloom Time
June to July
Fall Color
Insignificant
Origin
from Iran to central China
Phenological Calendar
As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Silk Tree typically reaches 'first bloom' at 3165 GDD₃₂, predicted around Jun 22.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,673 | Pre-season | 'First bloom' | 492 |
| Kent / Auburn | 2,665 | Pre-season | 'First bloom' | 500 |
| Seattle / UW | 2,610 | Pre-season | 'First bloom' | 555 |
| Olympia / Tumwater | 2,570 | Pre-season | 'First bloom' | 596 |
| Tacoma / Puyallup | 2,535 | Pre-season | 'First bloom' | 630 |
| Bellingham / Whatcom | 2,533 | Pre-season | 'First bloom' | 632 |
| Sequim / Rain Shadow | 2,436 | Pre-season | 'First bloom' | 730 |
View full calendar (2 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ 'First bloom' BBCH '61' NEXT | 3165 | '' est. Jun 22 (avg) |
| 'Full bloom' BBCH '65' | 3665 | '' est. Jul 8 (avg) |
Range: 2711–3098 GDD₃₂
(6yr)
Source: 'Master catalog (UMD), converted GDD50->GDD32 via Kent bloom-date mapping' About GDD₃₂ →
Season tracker for Kent / Auburn as of Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.
Cultivars (1)
'Summer Chocolate' Summer Chocolate®
Common name: Summer Chocolate Silk Tree; Mature height: 20 ft
Hardy to USDA Zone 6
Data Maturity Structured Multiple sources. Expert review underway.