American Hazel
'Leaf emergence'Corylus americana
Betulaceae · broadleaf deciduous shrub · native
Last updated
Quick Facts
Height
8–15 ft
Spread
8-13 ft
Growth Rate
Moderate
Light
Sun to Part Shade
Soil
Moist
Water
Moderate
Hardiness
Zone Zones 4a–8b
Bloom Time
March to April
Fall Color
Yellow, orange, red
Origin
from Newfoundland to Saskatchewan and south to eastern
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 14, 2026, Puget Sound stations range from 1926.1 to 2121.1 GDD₃₂. American Hazel has passed 'leaf emergence' (886 GDD₃₂).
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' | — | — |
| Kent / Auburn | 2,113 | 'Leaf emergence' | — | — |
| Seattle / UW | 2,085 | 'Leaf emergence' | — | — |
| Olympia / Tumwater | 2,047 | 'Leaf emergence' | — | — |
| Tacoma / Puyallup | 2,016 | 'Leaf emergence' | — | — |
| Bellingham / Whatcom | 1,994 | 'Leaf emergence' | — | — |
| Sequim / Rain Shadow | 1,926 | 'Leaf emergence' | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Full bloom' BBCH '65' | 394 | '' |
| 'First bloom' BBCH '61' | 461 | '' |
| 'Bud break' BBCH '07' | 879 | '' |
| ● 'Leaf emergence' BBCH '11' NOW | 886 | '' |
Source: 'NPN citizen science observations (WA+OR), n=5, 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.
Diseases: Regionally Documented (19)
Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Anisogramma anomala Eastern Filbert Blight Pseudomonas syringae pv. syringae Bacterial Blight Armillaria spp. — primarily A Armillaria Root Rot [VERIFY] Blanks Cryptosporella umbrina Brown Stain Symptom category — not a single disease Canker Catkin Blast Candidatus Phytoplasma pyri Decline/Collapse Syndrome Fungal agents (multiple) Kernel Molds Symptom category — not a single disease Leaf Spot Apple mosaic virus (ApMV) Mosaic Mosses and Lichens 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)
Malacosoma spp. Tent caterpillar Cnephasia longana Omnivorous leaftier Parthenolecanium spp. Lecanium scale Cydia latiferreana Filbertworm Archips rosanus Filbert Leafroller Phytoptus avellanae Filbert Bud Mite Myzocallis coryli Filbert Aphid Phenacoccus aceris Apple Mealybug Halyomorpha halys Brown marmorated stink bug
Data Maturity Structured Multiple sources. Expert review underway.