Chinese Lilac Rouen Lilac
'First bloom'Syringa chinensis
Oleaceae · broadleaf deciduous shrub · introduced
Last updated
Plant Profile
Size & Form
Height
8–15 ft
Growth Rate
Medium
Site Requirements
Light
Full Sun to Part Shade
Soil Drainage
Well Drained
Soil pH
neutral
Water
Moderate
Hardiness
Zones 3a–8b
Ornamental Interest
Fall Color
Purple
Watch for this season
Powdery MildewHigh
Active Conidial Spread
Oystershell scaleHigh
Crawler Emergence
Root weevilModerate
Adult Emergence & Foliar Feeding
Diseases: Regionally Documented (7)
Multiple obligate biotrophic fungi (Erysiphales: Erysipha... Powdery Mildew Pseudomonas syringae pv. syringae Bacterial Blight Gray Mold Symptom category — not a single disease Leaf Spot Lilac ring mottle virus Lilac Ring Mottle Phytophthora Canker and Shoot Blight Symptom category — not a single disease Root Rot
Pests: Regionally Documented (4)
Phenological Calendar
As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Chinese Lilac Rouen Lilac has passed 'first bloom' (1182 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 | 'First bloom' | — | — |
| Kent / Auburn | 2,665 | 'First bloom' | — | — |
| Seattle / UW | 2,610 | 'First bloom' | — | — |
| Olympia / Tumwater | 2,570 | 'First bloom' | — | — |
| Tacoma / Puyallup | 2,535 | 'First bloom' | — | — |
| Bellingham / Whatcom | 2,533 | 'First bloom' | — | — |
| Sequim / Rain Shadow | 2,436 | 'First bloom' | — | — |
View full calendar (2 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Bud break' BBCH '07' | 511 | '' |
| ● 'First bloom' BBCH '61' NOW | 1182 | '' |
Source: 'NPN citizen science observations (WA+OR), n=18, median. services.usanpn.org' 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.
Cultivars (1)
'Lilac Sunday'
Common name: Lilac Sunday Lilac; Mature height: 12 ft
Hardy to USDA Zone 3
Data Maturity Structured Multiple sources. Expert review underway.