Cutleaf Red Alder
'Fall color / leaf senescence'Alnus rubra f. pinnatisecta
Betulaceae · broadleaf deciduous tree · native
Last updated
This cutleaf form of red alder features deeply lobed leaves resembling delicate oak foliage, offering textural interest beyond the species' solid contribution to pioneer recovery. Like the straight species, it colonizes disturbed ground rapidly, reaching 90 feet at maturity and achieving 50 feet in just 20 years. Native to the Pacific coast from Alaska to California.
Red alder's greatest gift is nitrogen fixation through symbiotic root nodules that enrich impoverished soils, making it invaluable for erosion control and forest restoration. Plant it on wet ground, along streambanks, or in disturbed areas where its explosive growth accelerates recovery. Expect a short lifespan (60 to 80 years maximum) and watch for root rot, collar rot, and canker diseases; this tree is a temporary but essential component of forest succession, not a permanent specimen tree.
Plant Profile
Size & Form
Site Requirements
Ornamental Interest
Active Conidial Spread
Uredinial Stage (Summer)
Peak Population & Dispersal
Larval Feeding & Web Building
+ 3 more — see full disease and pest lists below
Diseases: Regionally Documented (11)
Pests: Regionally Documented (7)
Phenological Calendar
As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Cutleaf Red Alder has passed 'fall color / leaf senescence' (2063 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,673 | 'Fall color / leaf senescence' | — | — |
| Kent / Auburn | 2,665 | 'Fall color / leaf senescence' | — | — |
| Seattle / UW | 2,610 | 'Fall color / leaf senescence' | — | — |
| Olympia / Tumwater | 2,570 | 'Fall color / leaf senescence' | — | — |
| Tacoma / Puyallup | 2,535 | 'Fall color / leaf senescence' | — | — |
| Bellingham / Whatcom | 2,533 | 'Fall color / leaf senescence' | — | — |
| Sequim / Rain Shadow | 2,436 | 'Fall color / leaf senescence' | — | — |
View full calendar (6 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'First bloom' BBCH '61' | 844 | '' |
| 'Bud break' BBCH '07' | 854 | '' |
| 'Full bloom' BBCH '65' | 886 | '' |
| 'Flower buds visible' BBCH '51' | 1031 | '' |
| 'Leaf emergence' BBCH '11' | 1049 | '' |
| ● 'Fall color / leaf senescence' BBCH '93' NOW | 2063 | '' |
Source: 'NPN citizen science observations (WA+OR), n=106, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.