Speckled Alder

Alnus incana subsp. rugosa

Betulaceae · broadleaf deciduous shrub · native

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

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 24, 2026, Puget Sound stations range from 1455.1 to 1613.4 GDD₃₂. Speckled Alder has reached 'leaf emergence' (1353 GDD₃₂) and is approaching 'first bloom', predicted around May 8.

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 24, 2026
Station GDD₃₂ Current Stage Next To Go
Issaquah / East King 1,613 'Leaf emergence' 'First bloom' 250
Seattle / UW 1,574 'Leaf emergence' 'First bloom' 289
Kent / Auburn 1,559 'Leaf emergence' 'First bloom' 304
Olympia / Tumwater 1,524 'Leaf emergence' 'First bloom' 340
Bellingham / Whatcom 1,504 'Leaf emergence' 'First bloom' 359
Tacoma / Puyallup 1,492 'Leaf emergence' 'First bloom' 371
Sequim / Rain Shadow 1,455 'Leaf emergence' 'First bloom' 408
Stage GDD32 Typical Window
'Bud break' BBCH '07' 1353 ''
● 'Leaf emergence' BBCH '11' NOW 1353 ''
○ 'First bloom' BBCH '61' NEXT 1863 '' est. May 8 (forecast)
'Flower buds visible' BBCH '51' 1863 '' est. May 8 (forecast)
'Full bloom' BBCH '65' 1863 '' est. May 8 (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 24, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.

Diseases (11)

Pests (7)