Doublefile Viburnum
Viburnum plicatum
Viburnaceae · broadleaf deciduous shrub · introduced
Last updated
As of March 31, 2026, Kent / Auburn has accumulated 1062.5 GDD₃₂. Doublefile Viburnum typically reaches 'first bloom' at 1229 GDD₃₂, predicted around Apr 8.
Doublefile viburnum is one of the most architecturally dramatic shrubs available for Puget Sound landscapes. The horizontal tiered branching pattern displays white lacecap flowers along the upper surface of each branch, creating a layered wedding-cake effect in spring (353 GDD base 50 for 10% bloom). Growth is rapid and the plant reaches 8-15 feet with an 18-foot spread, so give it room. Purple-burgundy fall color is reliable. The plant prefers moist, well-drained soil; most lowland soils work if not waterlogged. 'Mariesii' is the classic cultivar with the most pronounced horizontal form. 'Summer Snowflake' reblooms sporadically through summer. Limited disease and pest data in our system suggests this is a relatively clean plant locally, but it has weed potential through self-seeding.
— Chris Welch, ISA Certified Arborist
Doublefile viburnum (Japanese snowball) is a deciduous shrub from Japan, China, and Taiwan reaching 8-15 ft with dense, spreading growth. It produces white flowers in spring with showy or non-showy forms depending on variety, and displays purple-burgundy fall color.
Doublefile viburnum is hardy in zones 5a-8b and grows in sun to part shade with moist to well-drained soil (pH 6.0-8.0). Growth is rapid with low maintenance. Flowers vary by cultivar from sterile (snowball types) to fertile forms. It attracts butterflies.
Quick Facts
Phenological Calendar
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Mar 31, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,132 | Pre-season | 'First bloom' | 97 |
| Seattle / UW | 1,126 | Pre-season | 'First bloom' | 103 |
| Kent / Auburn | 1,063 | Pre-season | 'First bloom' | 167 |
| Olympia / Tumwater | 1,062 | Pre-season | 'First bloom' | 167 |
| Bellingham / Whatcom | 1,053 | Pre-season | 'First bloom' | 176 |
| Tacoma / Puyallup | 1,030 | Pre-season | 'First bloom' | 199 |
| Sequim / Rain Shadow | 1,023 | Pre-season | 'First bloom' | 206 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ 'First bloom' BBCH '61' NEXT | 1229 | '' est. Apr 8 (forecast) |
| 'Full bloom' BBCH '65' | 1490 | '' est. Apr 20 (avg) |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? Hover over GDD values for source details. Season tracker for Kent / Auburn as of Mar 31, 2026. Predicted dates use 16-day weather forecast through Apr 16, 2026, then climate normals.