Green Hawthorn
Crataegus viridis
Rosaceae · broadleaf deciduous tree · native
Last updated
Data Coverage 4 of 6 dimensions
Quick Facts
Height
20–40 ft
Hardiness
Zone Zones 4a–8b
Bloom Time
May
Fall Color
Purple, scarlet
Origin
from Maryland, Virginia to Illinois
Phenological Calendar
As of April 12, 2026, Puget Sound stations range from 1235.8 to 1375.3 GDD₃₂. Green Hawthorn has reached 'first bloom' (1200 GDD₃₂) and is approaching 'full bloom', predicted around Apr 17.
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 | 'Full bloom' | — | — |
| Seattle / UW | 1,348 | 'First bloom' | 'Full bloom' | 22 |
| Kent / Auburn | 1,308 | 'First bloom' | 'Full bloom' | 62 |
| Olympia / Tumwater | 1,292 | 'First bloom' | 'Full bloom' | 78 |
| Bellingham / Whatcom | 1,270 | 'First bloom' | 'Full bloom' | 100 |
| Tacoma / Puyallup | 1,258 | 'First bloom' | 'Full bloom' | 112 |
| Sequim / Rain Shadow | 1,236 | 'First bloom' | 'Full bloom' | 134 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'First bloom' BBCH '61' NOW | 1200 | '' |
| ○ 'Full bloom' BBCH '65' NEXT | 1370 | '' est. Apr 17 (forecast) |
Range: 888–1070 GDD₃₂
(6yr)
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? Source GDD₅₀ thresholds from Herms 2004 (OSU, Secrest Arboretum, Ohio) and UMD IPMnet (Gill & Klick, mid-Atlantic), converted to GDD₃₂ via Kent bloom-date mapping. 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 (6)
Pests (12)
Tetranychidae Spider mite Coccoidea Scale insect Caliroa cerasi Pear slug Dysaphis crataegi Hawthorn aphid Choreutis pariana Apple-and-thorn skeletonizer Acanthococcus azaleae Azalea bark scale Enarmonia formosana Cherry bark tortrix Hyphantria cunea Fall webworm Tortricidae Leafroller Pear sawfly (pear slug) Malacosoma spp. Tent caterpillar Pear sawfly
Cultivars (1)
'Winter King'
Common name: Winter King Hawthorn Winter King Green Hawthorn; Mature height: 20–25 ft
Hardy to USDA Zone 4