Green Hawthorn

Crataegus viridis

Rosaceae · broadleaf deciduous tree · native

Last updated March 8, 2026

Data Coverage 4 of 6 dimensions

Site Data

Threats

Cultivars

Phenology

GDD Thresholds

Puget Sound

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 3, 2026, Puget Sound stations range from 1070 to 1180.6 GDD₃₂. Green Hawthorn typically reaches 'first bloom' at 1200 GDD₃₂, predicted around Apr 7.

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 3, 2026

Station	GDD₃₂	Current Stage	Next	To Go
Issaquah / East King	1,181	Pre-season	'First bloom'	19
Seattle / UW	1,171	Pre-season	'First bloom'	29
Kent / Auburn	1,111	Pre-season	'First bloom'	89
Olympia / Tumwater	1,106	Pre-season	'First bloom'	94
Bellingham / Whatcom	1,101	Pre-season	'First bloom'	99
Tacoma / Puyallup	1,075	Pre-season	'First bloom'	125
Sequim / Rain Shadow	1,070	Pre-season	'First bloom'	130

Stage	GDD₃₂	Typical Window	What to Look For
○ 'First bloom' BBCH '61' NEXT	1200	'' est. Apr 7 (forecast)	''
'Full bloom' BBCH '65'	1370	'' est. Apr 16 (forecast)	''

Regional estimate

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 3, 2026. Predicted dates use 16-day weather forecast through Apr 19, 2026, then climate normals.

Diseases (6)

Venturia inaequalis Scab Thekopsora minima and Naohidemyces vaccinii Rust Symptom category — not a single disease Leaf Spot Erwinia amylovora Fire Blight Symptom category — not a single disease Canker Podosphaera aphanis var. aphanis Powdery Mildew

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