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.
Plant Profile
Size & Form
Site Requirements
Ornamental Interest
Field Observations
Active Conidial Spread
Peak Population & Dispersal
Diseases: Regionally Documented (2)
Pests: Regionally Documented (3)
Phenological Calendar
As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Japanese Spirea has passed 'leaf emergence' (1624 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,673 | 'Leaf emergence' | — | — |
| Kent / Auburn | 2,665 | 'Leaf emergence' | — | — |
| Seattle / UW | 2,610 | 'Leaf emergence' | — | — |
| Olympia / Tumwater | 2,570 | 'Leaf emergence' | — | — |
| Tacoma / Puyallup | 2,535 | 'Leaf emergence' | — | — |
| Bellingham / Whatcom | 2,533 | 'Leaf emergence' | — | — |
| Sequim / Rain Shadow | 2,436 | 'Leaf emergence' | — | — |
View full calendar (1 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'Leaf emergence' BBCH '11' NOW | 1624 Observed | 'Late April' |
Source: 'Field observation, Kent, WA, 2026-04-27' About GDD₃₂ →
Season tracker for Kent / Auburn as of Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.