Common Filbert
Corylus avellana
Betulaceae · broadleaf deciduous shrub · introduced
Last updated
Data Coverage 5 of 6 dimensions
Quick Facts
Height
15 ft
Spread
9 ft
Growth Rate
Moderate
Light
Sun to Part Shade
Soil
Well Drained
Water
Moderate
Hardiness
Zone Zones 4a–8b
Bloom Time
February to March
Origin
Europe, Western Asia
Phenological Calendar
As of April 12, 2026, Puget Sound stations range from 1235.8 to 1375.3 GDD₃₂. Common Filbert has reached 'bud break' (1187 GDD₃₂) and is approaching 'leaf emergence', predicted around Apr 15.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 12, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,375 | 'Leaf emergence' | — | — |
| Seattle / UW | 1,348 | 'Leaf emergence' | — | — |
| Kent / Auburn | 1,308 | 'Bud break' | 'Leaf emergence' | 37 |
| Olympia / Tumwater | 1,292 | 'Bud break' | 'Leaf emergence' | 53 |
| Bellingham / Whatcom | 1,270 | 'Bud break' | 'Leaf emergence' | 75 |
| Tacoma / Puyallup | 1,258 | 'Bud break' | 'Leaf emergence' | 87 |
| Sequim / Rain Shadow | 1,236 | 'Bud break' | 'Leaf emergence' | 109 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'Bud break' BBCH '07' NOW | 1187 | '' |
| ○ 'Leaf emergence' BBCH '11' NEXT | 1345 | '' est. Apr 15 (forecast) |
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 12, 2026. Predicted dates use 16-day weather forecast through Apr 28, 2026, then climate normals.
Diseases (20)
Armillaria ostoyae Armillaria Root Rot Pseudomonas syringae pv. syringae Bacterial Blight [VERIFY] Blanks Cryptosporella umbrina Brown Stain Symptom category — not a single disease Canker Kalmusia coniothyrium Catkin Blast Candidatus Phytoplasma pyri Decline/Collapse Syndrome Anisogramma anomala Eastern Filbert Blight Fungal agents (multiple) Kernel Molds Symptom category — not a single disease Leaf Spot Apple mosaic virus (ApMV) Mosaic Non-pathogenic Mosses and Lichens Podosphaera aphanis var. aphanis Powdery Mildew Fumago vagans Sooty Mold Daffodil yellow stripe virus (DYVV) Stunt (Dilly) Non-pathogenic (abiotic — solar radiation damage) Sunburn Pythium spp. or Phytophthora spp. Wet Feet Taphrina wiesneri Witches' Broom Limb and Wood Decay Omnivorous leaftier
Pests (8)
Cultivars (4)
'Contorta'
Common name: Contorted Filbert Contorted Hazelnut Harry Lauder's Walking Stick; Mature height: 8–10 ft
Hardy to USDA Zone 4
'Red Dragon'
Common name: Red Dragon Hazelnut
Hardy to USDA Zone 4
'Red Majestic'
Common name: Red Majestic HazelnutRed Majestic Filbert
Hardy to USDA Zone 4
'Rote Zeller'
Common name: Rote Zeller Hazelnut
Hardy to USDA Zone 4