Japanese Spirea
'Leaf emergence'Spiraea japonica
Rosaceae · broadleaf deciduous shrub · introduced
Last updated
Japanese spirea is a deciduous shrub native to Japan and China, reaching 2-4 feet tall with small, lance-shaped leaves and flat clusters of pink to magenta flowers appearing mid- to late summer. The plant is compact and spreading.
Japanese spirea is hardy to zones 3-8 and thrives in full sun to light shade with well-drained soil and moderate moisture. It is fast-growing and responds well to pruning; regular pruning maintains shape and encourages dense bloom. Multiple cultivars are available with selections for flower color, foliage variegation, and compact size.
Quick Facts
Spring Emergence / Primary Infection
Spring Colonization
Field Observations
Phenological Calendar
As of May 13, 2026, Puget Sound stations range from 1906.2 to 2098.2 GDD₃₂. Japanese Spirea has passed 'leaf emergence' (1624 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 13, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,098 | 'Leaf emergence' | — | — |
| Kent / Auburn | 2,089 | 'Leaf emergence' | — | — |
| Seattle / UW | 2,063 | 'Leaf emergence' | — | — |
| Olympia / Tumwater | 2,025 | 'Leaf emergence' | — | — |
| Tacoma / Puyallup | 1,993 | 'Leaf emergence' | — | — |
| Bellingham / Whatcom | 1,972 | 'Leaf emergence' | — | — |
| Sequim / Rain Shadow | 1,906 | 'Leaf emergence' | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'Leaf emergence' BBCH '11' NOW | 1624 | 'Late April' |
Source: 'Field observation, Kent, WA, 2026-04-27' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 13, 2026. Predicted dates use 16-day weather forecast through May 29, 2026, then climate normals.