Persian Lilac
Syringa x persica
Oleaceae · [VERIFY] · introduced
Last updated
Persian lilac is a hybrid shrub reaching 6-10 feet tall with a more delicate, refined form than common lilac. The plant produces fragrant flowers in lighter shades of pink, purple, or white arranged in smaller, more elegant panicles appearing in late spring.
Persian lilac is hardy to zones 4-8 and thrives in full sun with well-drained soil. It is less coarse and more graceful than common lilac and is less susceptible to mildew in humid conditions. Multiple cultivars are available; the plants require pruning after flowering to maintain shape.
Quick Facts
Phenological Calendar
As of April 21, 2026, Puget Sound stations range from 1393.7 to 1554.7 GDD₃₂. Persian Lilac has passed full bloom (1364 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 21, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,555 | Full bloom | — | — |
| Seattle / UW | 1,516 | Full bloom | — | — |
| Kent / Auburn | 1,497 | Full bloom | — | — |
| Olympia / Tumwater | 1,467 | Full bloom | — | — |
| Bellingham / Whatcom | 1,440 | Full bloom | — | — |
| Tacoma / Puyallup | 1,434 | Full bloom | — | — |
| Sequim / Rain Shadow | 1,394 | Full bloom | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| Beginning of flowering BBCH 61 | 1080 | — |
| ● Full bloom BBCH 65 NOW | 1364 | — |
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 21, 2026. Predicted dates use 16-day weather forecast through May 7, 2026, then climate normals.