Speckled Alder

'Full bloom'

Alnus incana subsp. rugosa

Betulaceae · broadleaf deciduous shrub · native

Last updated

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
Watch for this season
Nectria CankerHigh

Spore Release (Fall & Spring Rains)

RustHigh

Aecial Stage (Alternate Host)

Tent caterpillarHigh

Larval Feeding

Armillaria Root RotModerate

Active Below-ground Growth

+ 4 more — see full disease and pest lists below

Phenological Calendar

As of May 14, 2026, Puget Sound stations range from 1926.1 to 2121.1 GDD₃₂. Speckled Alder has passed 'full bloom' (1863 GDD₃₂).

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of May 14, 2026
Station GDD₃₂ Current Stage Next To Go
Issaquah / East King 2,121 'Full bloom' — —
Kent / Auburn 2,113 'Full bloom' — —
Seattle / UW 2,085 'Full bloom' — —
Olympia / Tumwater 2,047 'Full bloom' — —
Tacoma / Puyallup 2,016 'Full bloom' — —
Bellingham / Whatcom 1,994 'Full bloom' — —
Sequim / Rain Shadow 1,926 'Full bloom' — —
Stage GDD32 Typical Window
'Bud break' BBCH '07' 1353 ''
'Leaf emergence' BBCH '11' 1353 ''
'First bloom' BBCH '61' 1863 ''
'Flower buds visible' BBCH '51' 1863 ''
● 'Full bloom' BBCH '65' NOW 1863 ''

Source: 'NPN citizen science observations (WA+OR), n=36, median. services.usanpn.org' About GDD₃₂ →

Season tracker for Kent / Auburn as of May 14, 2026. Predicted dates use 16-day weather forecast through May 30, 2026, then climate normals.

Diseases: Regionally Documented (11)

Pests: Regionally Documented (7)

Data Maturity
Structured Multiple sources. Expert review underway.