Butterfly bush
Buddleia hemsleyana
Scrophulariaceae · [VERIFY] · introduced
Last updated
Semi-woody deciduous shrub with narrow, lance-shaped foliage and terminal panicles of small tubular flowers in late summer and fall. Flowers range from white to pale lilac and are highly fragrant, attracting butterflies and pollinators.
Requires warm, sheltered sites and full sun. Prefers well-drained soil; drought tolerant when established. Less aggressive than B. davidii; treated as herbaceous perennial in cooler climates. Prune hard in late winter for vigor.
Quick Facts
Phenological Calendar
As of May 24, 2026, Puget Sound stations range from 2172.5 to 2394 GDD₃₂. Butterfly bush typically reaches beginning of flowering at 3352 GDD₃₂, predicted around Jun 28.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 24, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,394 | Pre-season | Beginning of flowering | 958 |
| Kent / Auburn | 2,373 | Pre-season | Beginning of flowering | 979 |
| Seattle / UW | 2,332 | Pre-season | Beginning of flowering | 1,020 |
| Olympia / Tumwater | 2,295 | Pre-season | Beginning of flowering | 1,057 |
| Tacoma / Puyallup | 2,259 | Pre-season | Beginning of flowering | 1,093 |
| Bellingham / Whatcom | 2,256 | Pre-season | Beginning of flowering | 1,097 |
| Sequim / Rain Shadow | 2,173 | Pre-season | Beginning of flowering | 1,180 |
View full calendar (1 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Beginning of flowering BBCH 61 NEXT | 3352 | — est. Jun 28 (avg) |
Source: UMD phenology catalog (UMD: extension.umd.edu) About GDD₃₂ →
Season tracker for Kent / Auburn as of May 24, 2026. Predicted dates use 16-day weather forecast through Jun 9, 2026, then climate normals.