Western Hazel
Corylus cornuta var. californica
Betulaceae · broadleaf deciduous shrub · native
Last updated
This profile contains verified botanical data. Regional field notes and expert review are in progress.
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
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Western Hazel has reached 'leaf emergence' (1161 GDD₃₂) and is approaching 'fall color / leaf senescence', 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 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,415 |
| Seattle / UW | 1,554 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,454 |
| Kent / Auburn | 1,537 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,471 |
| Olympia / Tumwater | 1,505 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,504 |
| Bellingham / Whatcom | 1,483 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,525 |
| Tacoma / Puyallup | 1,472 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,536 |
| Sequim / Rain Shadow | 1,434 | 'Leaf emergence' | 'Fall color / leaf senescence' | 1,574 |
| 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 23 (avg) |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? GDD₃₂ thresholds from USA National Phenology Network citizen science observations (WA+OR). Season tracker for Kent / Auburn as of Apr 23, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.