Butterfly weed
Asclepias tuberosa
Apocynaceae · [VERIFY] · introduced
Last updated
Tuberous-rooted perennial to 1 to 2 feet tall forming bright orange to yellow-orange flower clusters on upright to reclining hairy stems with narrow, lance-shaped leaves. Unlike other milkweeds, lacks milky-sapped stems.
Slow to establish (expect 2 to 3 years to flowering), but worth the wait for drought tolerance and showy blooms; thrives in poor, dry, well-drained soils in full sun. Does not transplant well due to deep taproot; best used in rock gardens, prairies, meadows, or native plant areas.
Quick Facts
Phenological Calendar
As of May 24, 2026, Puget Sound stations range from 2172.5 to 2394 GDD₃₂. Butterfly weed typically reaches beginning of flowering at 3405 GDD₃₂, predicted around Jun 30.
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 | 1,011 |
| Kent / Auburn | 2,373 | Pre-season | Beginning of flowering | 1,032 |
| Seattle / UW | 2,332 | Pre-season | Beginning of flowering | 1,073 |
| Olympia / Tumwater | 2,295 | Pre-season | Beginning of flowering | 1,110 |
| Tacoma / Puyallup | 2,259 | Pre-season | Beginning of flowering | 1,146 |
| Bellingham / Whatcom | 2,256 | Pre-season | Beginning of flowering | 1,150 |
| Sequim / Rain Shadow | 2,173 | Pre-season | Beginning of flowering | 1,233 |
View full calendar (1 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Beginning of flowering BBCH 61 NEXT | 3405 | — est. Jun 30 (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.