Mountain pieris
Pieris floribunda
Ericaceae · [VERIFY] · native
Last updated
Pieris floribunda (Ericaceae) is a broadleaf evergreen shrub native to the Appalachian Mountains of the southeastern United States. It grows 4 to 6 feet tall with a rounded, dense habit. Upright panicles of small, white, urn-shaped flowers appear in early spring. Unlike P. japonica, the flower clusters are held upright rather than pendulous.
Mountain pieris requires acidic, moist, well-drained soil in part shade. It is hardier and more resistant to lace bug than P. japonica. Growth is slow. No significant disease problems are documented beyond those common to ericaceous plants. Hardy in Zones 4 to 6.
Quick Facts
Phenological Calendar
As of April 19, 2026, Puget Sound stations range from 1342.9 to 1500.8 GDD₃₂. Mountain pieris has passed full bloom (1143 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 19, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,501 | Full bloom | — | — |
| Seattle / UW | 1,465 | Full bloom | — | — |
| Kent / Auburn | 1,441 | Full bloom | — | — |
| Olympia / Tumwater | 1,415 | Full bloom | — | — |
| Bellingham / Whatcom | 1,390 | Full bloom | — | — |
| Tacoma / Puyallup | 1,381 | Full bloom | — | — |
| Sequim / Rain Shadow | 1,343 | Full bloom | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● Full bloom BBCH 65 NOW | 1143 | — |
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 19, 2026. Predicted dates use 16-day weather forecast through May 5, 2026, then climate normals.