Multiflora Rose
Rosa multiflora
Rosaceae · broadleaf deciduous shrub · naturalized
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Multiflora rose (Rosa multiflora) is a broadleaf shrub in the Rosaceae family native to Japan and Korea, now widely naturalized in North America. It reaches 15 ft tall and produces white fragrant conical flower clusters with flowers approximately 2 cm across. It originally grows on slopes and scrub in eastern Asia.
Multiflora rose is hardy in zones 5a-8b and prefers full sun with moist soil (pH 4.5-8.5). It has high maintenance requirements. Twenty-seven diseases and 29 pests are documented. The species has significant weed and invasive potential and is classified as a noxious weed in multiple states.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Multiflora Rose typically reaches beginning of flowering at 2082 GDD₃₂, predicted around May 19.
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 | Pre-season | Beginning of flowering | 489 |
| Seattle / UW | 1,554 | Pre-season | Beginning of flowering | 528 |
| Kent / Auburn | 1,537 | Pre-season | Beginning of flowering | 545 |
| Olympia / Tumwater | 1,505 | Pre-season | Beginning of flowering | 578 |
| Bellingham / Whatcom | 1,483 | Pre-season | Beginning of flowering | 599 |
| Tacoma / Puyallup | 1,472 | Pre-season | Beginning of flowering | 610 |
| Sequim / Rain Shadow | 1,434 | Pre-season | Beginning of flowering | 648 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Beginning of flowering BBCH 61 NEXT | 2082 | — est. May 19 (avg) |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? Source GDD₅₀ thresholds from Herms 2004 (OSU, Secrest Arboretum, Ohio) and UMD IPMnet (Gill & Klick, mid-Atlantic), converted to GDD₃₂ via Kent bloom-date mapping. Season tracker for Kent / Auburn as of Apr 23, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.