American Holly
Ilex opaca
Aquifoliaceae · [VERIFY] · [VERIFY]
Last updated
Data Coverage 3 of 6 dimensions
Quick Facts
Light
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Soil
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Hardiness
Zone Zone [VERIFY]
Origin
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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 | 1,228 |
| Olympia / Tumwater | 816 | Pre-season | Beginning of flowering | 1,297 |
| Bellingham / Whatcom | 816 | Pre-season | Beginning of flowering | 1,297 |
| Kent / Auburn | 805 | Pre-season | Beginning of flowering | 1,308 |
| Sequim / Rain Shadow | 798 | Pre-season | Beginning of flowering | 1,315 |
| Tacoma / Puyallup | 792 | Pre-season | Beginning of flowering | 1,321 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Beginning of flowering BBCH 61 NEXT | 2113 | — est. May 24 (avg) |
| Full bloom BBCH 65 | 2440 | — est. Jun 6 (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.