Thimbleberry Western Thimbleberry
Rubus parviflorus
Rosaceae · broadleaf deciduous shrub · native
Last updated
This profile contains verified botanical data. Regional field notes and expert review are in progress.
Thimbleberry (Rubus parviflorus), also called western thimbleberry, is a broadleaf deciduous shrub in the Rosaceae family native to western North America. It reaches 3-8 ft tall with a 6 ft spread and forms thickets via rhizomatous spread. White (rarely pinkish) crinkled flowers 3-5 cm across appear in loose corymbs. It occurs in woodlands and canyons.
Thimbleberry is hardy in zones 3a-8b and tolerates full sun to shade with moist soil (pH 4.5-8.5) and moderate water with medium maintenance. Thirty-one diseases are documented with no pest records. The fruit has a moderate edibility rating (3/5) and moderate culinary and medicinal value.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Thimbleberry Western Thimbleberry has reached 'flower buds visible' (1490 GDD₃₂) and is approaching 'first bloom', predicted around May 8.
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 | 'Flower buds visible' | 'First bloom' | 262 |
| Seattle / UW | 1,554 | 'Flower buds visible' | 'First bloom' | 301 |
| Kent / Auburn | 1,537 | 'Flower buds visible' | 'First bloom' | 318 |
| Olympia / Tumwater | 1,505 | 'Flower buds visible' | 'First bloom' | 351 |
| Bellingham / Whatcom | 1,483 | 'Leaf emergence' | 'Flower buds visible' | 7 |
| Tacoma / Puyallup | 1,472 | 'Leaf emergence' | 'Flower buds visible' | 18 |
| Sequim / Rain Shadow | 1,434 | 'Leaf emergence' | 'Flower buds visible' | 56 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Bud break' BBCH '07' | 817 | '' |
| 'Leaf emergence' BBCH '11' | 1305 | '' |
| ● 'Flower buds visible' BBCH '51' NOW | 1490 | '' |
| ○ 'First bloom' BBCH '61' NEXT | 1855 | '' est. May 8 (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 23, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.