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Speckled Alder

Alnus incana subsp. rugosa

Betulaceae · broadleaf deciduous shrub · native

Last updated

Data Coverage 4 of 6 dimensions
Site Data
Threats
Cultivars
Phenology
GDD Thresholds
Puget Sound

Quick Facts

Height
20 ft
Growth Rate
Fast
Light
Sun to Part Shade
Soil
Wet Tolerant
Water
High
Hardiness
Zone Zones 2a–8b
Bloom Time
March
Origin
is eastern North America, it is most common in the Great

Phenological Calendar

As of April 3, 2026, Puget Sound stations range from 1070 to 1180.6 GDD₃₂. Speckled Alder typically reaches 'bud break' at 1353 GDD₃₂, predicted around Apr 15.

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 'Bud break' 172
Seattle / UW 1,171 Pre-season 'Bud break' 182
Kent / Auburn 1,111 Pre-season 'Bud break' 242
Olympia / Tumwater 1,106 Pre-season 'Bud break' 247
Bellingham / Whatcom 1,101 Pre-season 'Bud break' 252
Tacoma / Puyallup 1,075 Pre-season 'Bud break' 278
Sequim / Rain Shadow 1,070 Pre-season 'Bud break' 283
Stage GDD32 Typical Window
○ 'Bud break' BBCH '07' NEXT 1353 '' est. Apr 15 (forecast)
'Leaf emergence' BBCH '11' 1353 '' est. Apr 15 (forecast)
'First bloom' BBCH '61' 1863 '' est. May 10 (avg)
'Flower buds visible' BBCH '51' 1863 '' est. May 10 (avg)
'Full bloom' BBCH '65' 1863 '' est. May 10 (avg)

GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? GDD₃₂ thresholds from USA National Phenology Network citizen science observations (WA+OR). 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 (11)

Pests (7)