Western Hazel
Corylus cornuta var. californica
Betulaceae · broadleaf deciduous shrub · native
Last updated
You recognize California Hazelnut by its rounded habit, heart-shaped deciduous leaves, and distinctive tubular involucre (burr) enclosing edible hazelnuts throughout the understory of coastal California oak and conifer forests, with northern populations in southwestern Oregon.
California Hazelnut reaches 6-12 feet tall in sun to part shade with moderate water needs and excellent drought tolerance once established. It thrives in well-drained, adaptable soils and tolerates poor fertility. Fast-growing with modest lifespan, it suits woodland gardens and native hedgerows. Watch for eastern filbert blight (not yet documented in California populations), powdery mildew, and root weevils. Nuthatches and squirrels harvest nuts readily; wildlife value is substantial.
Quick Facts
Spring Infection Period
Wound Infection Window
Active Below-ground Growth
Spring Emergence / Primary Infection
+ 1 more — see full disease and pest lists below
Phenological Calendar
As of May 14, 2026, Puget Sound stations range from 1926.1 to 2121.1 GDD₃₂. Western Hazel has reached 'leaf emergence' (1161 GDD₃₂) and is approaching 'fall color / leaf senescence', predicted around Jun 18.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 14, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,121 | 'Leaf emergence' | 'Fall color / leaf senescence' | 887 |
| Kent / Auburn | 2,113 | 'Leaf emergence' | 'Fall color / leaf senescence' | 895 |
| Seattle / UW | 2,085 | 'Leaf emergence' | 'Fall color / leaf senescence' | 923 |
| Olympia / Tumwater | 2,047 | 'Leaf emergence' | 'Fall color / leaf senescence' | 961 |
| Tacoma / Puyallup | 2,016 | 'Leaf emergence' | 'Fall color / leaf senescence' | 992 |
| Bellingham / Whatcom | 1,994 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,014 |
| Sequim / Rain Shadow | 1,926 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,082 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'First bloom' BBCH '61' | 557 | '' |
| 'Flower buds visible' BBCH '51' | 710 | '' |
| 'Full bloom' BBCH '65' | 800 | '' |
| 'Bud break' BBCH '07' | 1097 | '' |
| ● 'Leaf emergence' BBCH '11' NOW | 1161 | '' |
| ○ 'Fall color / leaf senescence' BBCH '93' NEXT | 3008 | '' est. Jun 18 (avg) |
Source: 'NPN citizen science observations (WA+OR), n=182, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 14, 2026. Predicted dates use 16-day weather forecast through May 30, 2026, then climate normals.