Oregon Grape
Berberis aquifolium
Berberidaceae · broadleaf evergreen shrub · native
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Oregon grape is one of the three signature native understory shrubs on Puget Sound lowlands, occurring naturally alongside sword fern and salal. Tolerates the wet-winter/dry-summer moisture cycle of Alderwood soil and the persistent moisture of Woodinville silt loam. Often used in rain gardens and riparian buffers. Spreads by rhizomes; can become weedy in contained plantings. Winter foliage turns burgundy-purple after first frost. Early yellow flowers (March-April) are a pollen source for native bees.
— Chris Welch, ISA Certified Arborist
Oregon grape (Berberis aquifolium, Berberidaceae) is an erect, fast-growing broadleaf evergreen shrub reaching 3 to 6 feet tall and 5 feet wide, native to western North America. Pinnately compound leaves with spiny, holly-like leaflets emerge glossy green and turn purple-red in cold weather. Fragrant yellow flowers appear in racemes in spring, followed by tart, dark bluish-black berries. The plant spreads by stolons and suckers freely, forming dense colonies over time.
Oregon grape grows best in part shade to full shade on moist, well-drained, acidic soil; full sun can bleach foliage. It tolerates renovation pruning with up to 90 to 95 percent removal if rejuvenation is needed. Documented pest associations include brown soft scale, cottony camellia scale, spider mites, and holly leafminer. Diseases to monitor include powdery mildew, rust, and leaf spot. Seven cultivars are documented in the trade.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Oregon Grape has passed 'bud break' (1201 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' | 995 | '' |
| 'First bloom' BBCH '61' | 1084 | '' |
| 'Full bloom' BBCH '65' | — | '' |
| ● 'Bud break' BBCH '07' NOW | 1201 | '' |
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 10, 2026, then climate normals.