Scotch Broom
Cytisus scoparius
Fabaceae · broadleaf deciduous shrub · introduced
Last updated
Data Maturity Baseline
This profile contains verified botanical data. Regional field notes and expert review are in progress.
Quick Facts
Height
4–8 ft
Spread
4–8 ft
Growth Rate
Fast
Light
Full Sun
Soil
Moist
Water
Moderate
Hardiness
Zone Zones 5–6
Bloom Time
May to June
Origin
central and southern Europe
Phenological Calendar
As of April 29, 2026, Puget Sound stations range from 1558.2 to 1719 GDD₃₂. Scotch Broom has passed 'first bloom' (1539 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 29, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,719 | 'First bloom' | — | — |
| Seattle / UW | 1,676 | 'First bloom' | — | — |
| Kent / Auburn | 1,670 | 'First bloom' | — | — |
| Olympia / Tumwater | 1,626 | 'First bloom' | — | — |
| Bellingham / Whatcom | 1,615 | 'First bloom' | — | — |
| Tacoma / Puyallup | 1,595 | 'First bloom' | — | — |
| Sequim / Rain Shadow | 1,558 | 'First bloom' | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Fall color / leaf senescence' BBCH '93' | 1018 | '' |
| 'Bud break' BBCH '07' | 1084 | '' |
| 'Flower buds visible' BBCH '51' | 1304 | '' |
| 'Leaf emergence' BBCH '11' | 1337 | '' |
| ● 'First bloom' BBCH '61' NOW | 1539 | '' |
Range: 1177–1952 GDD₃₂
(8yr) · 36 obs
Source: 'NPN citizen science observations (WA+OR), n=10, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of Apr 29, 2026. Predicted dates use 16-day weather forecast through May 15, 2026, then climate normals.