Common Filbert
'Leaf emergence'Corylus avellana
Betulaceae · broadleaf deciduous shrub · introduced
Last updated
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
Fall Color
Yellow
Origin
Europe, Western Asia
Watch for this season
Bacterial BlightHigh
Spring Infection Period
Wood DecayHigh
Wound Infection Window
Tent caterpillarHigh
Larval Feeding
Armillaria Root RotModerate
Active Below-ground Growth
+ 3 more — see full disease and pest lists below
Phenological Calendar
As of May 13, 2026, Puget Sound stations range from 1906.2 to 2098.2 GDD₃₂. Common Filbert has passed 'leaf emergence' (1345 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 13, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,098 | 'Leaf emergence' | — | — |
| Kent / Auburn | 2,089 | 'Leaf emergence' | — | — |
| Seattle / UW | 2,063 | 'Leaf emergence' | — | — |
| Olympia / Tumwater | 2,025 | 'Leaf emergence' | — | — |
| Tacoma / Puyallup | 1,993 | 'Leaf emergence' | — | — |
| Bellingham / Whatcom | 1,972 | 'Leaf emergence' | — | — |
| Sequim / Rain Shadow | 1,906 | 'Leaf emergence' | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Bud break' BBCH '07' | 1187 | '' |
| ● 'Leaf emergence' BBCH '11' NOW | 1345 | '' |
Source: 'NPN citizen science observations (WA+OR), n=5, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 13, 2026. Predicted dates use 16-day weather forecast through May 29, 2026, then climate normals.
Diseases: Regionally Documented (19)
Armillaria spp. — primarily A Armillaria Root Rot Pseudomonas syringae pv. syringae Bacterial Blight [VERIFY] Blanks Cryptosporella umbrina Brown Stain Symptom category — not a single disease Canker 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 Mosses and Lichens Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Fumago vagans Sooty Mold Daffodil yellow stripe virus (DYVV) Stunt (Dilly) Sunburn Wet Feet Taphrina wiesneri Witches' Broom Multiple Basidiomycete fungi cause wood decay in trees Wood Decay
Pests: Regionally Documented (9)
Cnephasia longana Omnivorous leaftier Phenacoccus aceris Apple Mealybug Halyomorpha halys Brown marmorated stink bug Myzocallis coryli Filbert Aphid Phytoptus avellanae Filbert Bud Mite Archips rosanus Filbert Leafroller Cydia latiferreana Filbertworm Parthenolecanium spp. Lecanium scale Malacosoma spp. Tent caterpillar
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
Data Maturity Structured Multiple sources. Expert review underway.