Garland Spirea
Spiraea arguta
Rosaceae · broadleaf deciduous shrub · introduced
Last updated
Data Coverage 3 of 6 dimensions
Quick Facts
Height
5–6 ft
Light
Full Sun to Shade
Hardiness
Zone Zones 4a–8b
Phenological Calendar
As of April 3, 2026, Puget Sound stations range from 1070 to 1180.6 GDD₃₂. Garland Spirea has reached 'full bloom' (923 GDD₃₂) and is approaching 'first bloom', predicted around Apr 17.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,181 | 'Full bloom' | 'First bloom' | 210 |
| Seattle / UW | 1,171 | 'Full bloom' | 'First bloom' | 220 |
| Kent / Auburn | 1,111 | 'Full bloom' | 'First bloom' | 280 |
| Olympia / Tumwater | 1,106 | 'Full bloom' | 'First bloom' | 285 |
| Bellingham / Whatcom | 1,101 | 'Full bloom' | 'First bloom' | 290 |
| Tacoma / Puyallup | 1,075 | 'Full bloom' | 'First bloom' | 316 |
| Sequim / Rain Shadow | 1,070 | 'Full bloom' | 'First bloom' | 321 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'Full bloom' BBCH '65' NOW | 923 | '' |
| ○ 'First bloom' BBCH '61' NEXT | 1391 | '' est. Apr 17 (forecast) |
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 3, 2026. Predicted dates use 16-day weather forecast through Apr 19, 2026, then climate normals.