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 21, 2026, Puget Sound stations range from 1393.7 to 1554.7 GDD₃₂. Speckled Alder has reached 'leaf emergence' (1353 GDD₃₂) and is approaching 'first bloom', predicted around May 5.

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 21, 2026
Station GDD₃₂ Current Stage Next To Go
Issaquah / East King 1,555 'Leaf emergence' 'First bloom' 308
Seattle / UW 1,516 'Leaf emergence' 'First bloom' 347
Kent / Auburn 1,497 'Leaf emergence' 'First bloom' 366
Olympia / Tumwater 1,467 'Leaf emergence' 'First bloom' 396
Bellingham / Whatcom 1,440 'Leaf emergence' 'First bloom' 423
Tacoma / Puyallup 1,434 'Leaf emergence' 'First bloom' 429
Sequim / Rain Shadow 1,394 'Leaf emergence' 'First bloom' 469
Stage GDD32 Typical Window
'Bud break' BBCH '07' 1353 ''
● 'Leaf emergence' BBCH '11' NOW 1353 ''
○ 'First bloom' BBCH '61' NEXT 1863 '' est. May 5 (forecast)
'Flower buds visible' BBCH '51' 1863 '' est. May 5 (forecast)
'Full bloom' BBCH '65' 1863 '' est. May 5 (forecast)

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 21, 2026. Predicted dates use 16-day weather forecast through May 7, 2026, then climate normals.

Diseases (11)

Pests (7)