Longleaf Mahonia Cascade Mahonia
Berberis nervosa
Berberidaceae · broadleaf evergreen shrub · native
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Longleaf mahonia (Berberis nervosa, Berberidaceae) is a low-growing broadleaf evergreen native to western North America, typically staying under 2 feet tall though leaves can reach 7 feet on exceptional sites. Each compound leaf carries 9 to 21 strongly toothed, holly-like leaflets up to 3 inches long. Yellow flowers appear in spring, followed by dark edible berries. The plant spreads by underground rhizomes and is fire-adapted, resprouting readily after burns.
Longleaf mahonia grows in sun to shade across a range of soil types and moisture levels, from sea level to 1,800 meters elevation. It tolerates renovation pruning with up to 90 to 95 percent removal. Documented diseases include leaf spot, rust, leaf scorch, and powdery mildew; lecanium scale is the primary pest association. Its low, rhizomatous habit makes it useful as a groundcover in woodland and naturalized settings.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Longleaf Mahonia Cascade Mahonia has passed 'bud break' (1242 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 23, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,593 | 'Bud break' | — | — |
| Seattle / UW | 1,554 | 'Bud break' | — | — |
| Kent / Auburn | 1,537 | 'Bud break' | — | — |
| Olympia / Tumwater | 1,505 | 'Bud break' | — | — |
| Bellingham / Whatcom | 1,483 | 'Bud break' | — | — |
| Tacoma / Puyallup | 1,472 | 'Bud break' | — | — |
| Sequim / Rain Shadow | 1,434 | 'Bud break' | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Flower buds visible' BBCH '51' | 926 | '' |
| 'First bloom' BBCH '61' | 1144 | '' |
| ● 'Bud break' BBCH '07' NOW | 1242 | '' |
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 23, 2026. Predicted dates use 16-day weather forecast through May 9, 2026, then climate normals.