Yellow flag iris
Iris pseudacorus
Iridaceae · [VERIFY] · [VERIFY]
Last updated
Data Coverage 3 of 6 dimensions
Quick Facts
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Hardiness
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Phenological Calendar
Regional Season Tracker
GDD₃₂ accumulation across 6 Puget Sound stations · as of Mar 14, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Seattle / UW | 885 | Pre-season | Beginning of flowering | 1,399 |
| Olympia / Tumwater | 816 | Pre-season | Beginning of flowering | 1,468 |
| Bellingham / Whatcom | 816 | Pre-season | Beginning of flowering | 1,468 |
| Kent / Auburn | 805 | Pre-season | Beginning of flowering | 1,479 |
| Sequim / Rain Shadow | 798 | Pre-season | Beginning of flowering | 1,486 |
| Tacoma / Puyallup | 792 | Pre-season | Beginning of flowering | 1,492 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Beginning of flowering BBCH 61 NEXT | 2284 | — est. May 31 (avg) |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Thresholds calibrated for Western WA maritime climate from field observation and PNW bloom timing estimates. Season tracker for Kent / Auburn as of Mar 14, 2026. Predicted dates use 16-day weather forecast through Mar 31, 2026, then climate normals.