Longleaf Mahonia Cascade Mahonia
Berberis nervosa
Berberidaceae · broadleaf evergreen shrub · native
Last updated
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 3, 2026, Puget Sound stations range from 1070 to 1180.6 GDD₃₂. Longleaf Mahonia Cascade Mahonia has reached 'flower buds visible' (926 GDD₃₂) and is approaching 'first bloom', predicted around Apr 5.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,181 | 'First bloom' | 'Bud break' | 61 |
| Seattle / UW | 1,171 | 'First bloom' | 'Bud break' | 71 |
| Kent / Auburn | 1,111 | 'Flower buds visible' | 'First bloom' | 33 |
| Olympia / Tumwater | 1,106 | 'Flower buds visible' | 'First bloom' | 38 |
| Bellingham / Whatcom | 1,101 | 'Flower buds visible' | 'First bloom' | 43 |
| Tacoma / Puyallup | 1,075 | 'Flower buds visible' | 'First bloom' | 69 |
| Sequim / Rain Shadow | 1,070 | 'Flower buds visible' | 'First bloom' | 74 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'Flower buds visible' BBCH '51' NOW | 926 | '' |
| ○ 'First bloom' BBCH '61' NEXT | 1144 | '' est. Apr 5 (forecast) |
| 'Bud break' BBCH '07' | 1242 | '' est. Apr 9 (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 3, 2026. Predicted dates use 16-day weather forecast through Apr 19, 2026, then climate normals.