Carolina Silverbell Mountain Silverbell
Halesia carolina
Styracacaceae · broadleaf deciduous tree · native
Last updated
Data Coverage 3 of 6 dimensions
Quick Facts
Height
30–40 ft
Spread
32 ft
Growth Rate
Moderate
Light
Part Shade
Soil
Wet Tolerant
Water
Moderate
Hardiness
Zone Zones 4a–8b
Bloom Time
April
Origin
the Appalachians Mountains of North Carolina to Tennessee
Phenological Calendar
As of April 19, 2026, Puget Sound stations range from 1342.9 to 1500.8 GDD₃₂. Carolina Silverbell Mountain Silverbell has passed full bloom (1197 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 |
|---|---|---|
| Bloom start BBCH 61 | 959 | Apr 1-Apr 30 |
| ● Full bloom BBCH 65 NOW | 1197 | — |
| Bud break BBCH 07 | — | Feb 15-Mar 15 |
| Leaf emergence BBCH 11 | — | Mar 1-Apr 1 |
| Bloom end / petal fall BBCH 69 | — | Apr 15-May 15 |
| Fruit/seed development BBCH 71 | — | Jun 1-Aug 31 |
| Fruit/seed maturity BBCH 85 | — | Sep 1-Nov 30 |
| Fall color / leaf senescence BBCH 93 | — | Oct 1-Nov 15 |
| Dormancy BBCH 97 | — | Nov 15-Feb 28 |
Range: 635–790 GDD₃₂
(6yr)
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.