American Hazel
'Leaf emergence'Corylus americana
Betulaceae · broadleaf deciduous shrub · introduced
Last updated
Plant Profile
Size & Form
Height
8–15 ft
Spread
8-13 ft
Growth Rate
Moderate
Size at 20 yr
10 ft
Lifespan
Short-lived
Site Requirements
Light
Sun to Part Shade
Soil Drainage
Moist
Soil pH
5.0-7.0
Water
Moderate
Drought Tolerance
Medium
Hardiness
Zones 4a–8b
Ornamental Interest
Bloom Time
March to April
Fall Color
Yellow, orange, red
Origin
from Newfoundland to Saskatchewan and south to eastern
Watch for this season
Powdery MildewHigh
Active Conidial Spread
Wood DecayHigh
Wound Infection Window
Armillaria Root RotModerate
Active Below-ground Growth
Sooty MoldModerate
Heavy Mold Colonization
+ 1 more — see full disease and pest lists below
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
Phenological Calendar
As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. American Hazel has passed 'leaf emergence' (886 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,673 | 'Leaf emergence' | — | — |
| Kent / Auburn | 2,665 | 'Leaf emergence' | — | — |
| Seattle / UW | 2,610 | 'Leaf emergence' | — | — |
| Olympia / Tumwater | 2,570 | 'Leaf emergence' | — | — |
| Tacoma / Puyallup | 2,535 | 'Leaf emergence' | — | — |
| Bellingham / Whatcom | 2,533 | 'Leaf emergence' | — | — |
| Sequim / Rain Shadow | 2,436 | 'Leaf emergence' | — | — |
View full calendar (4 stages)
| 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 Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.
Data Maturity Structured Multiple sources. Expert review underway.