Northern Lights Forsythia
Full bloomForsythia x intermedia
Oleaceae · [VERIFY] · introduced
Last updated
Deciduous shrub growing 6 to 8 feet tall with bright yellow four-lobed flowers covering arching stems in early spring before leaf emergence. Foliage is medium green; form is loose and spreading.
Hardy, low-maintenance spring accent shrub thriving in full sun to light shade and adaptable soils. Prune after flowering to shape; old canes can be removed at the base. No significant pests or diseases; tends toward leggy growth without selective pruning.
Quick Facts
Phenological Calendar
As of May 15, 2026, Puget Sound stations range from 1942.5 to 2137.2 GDD₃₂. Northern Lights Forsythia has passed full bloom (686 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 15, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,137 | Full bloom | — | — |
| Kent / Auburn | 2,130 | Full bloom | — | — |
| Seattle / UW | 2,102 | Full bloom | — | — |
| Olympia / Tumwater | 2,064 | Full bloom | — | — |
| Tacoma / Puyallup | 2,033 | Full bloom | — | — |
| Bellingham / Whatcom | 2,012 | Full bloom | — | — |
| Sequim / Rain Shadow | 1,943 | Full bloom | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| Beginning of flowering BBCH 61 | 423 | — |
| ● Full bloom BBCH 65 NOW | 686 | — |
Source: UMD: extension.umd.edu) About GDD₃₂ →
Season tracker for Kent / Auburn as of May 15, 2026. Predicted dates use 16-day weather forecast through May 31, 2026, then climate normals.