Catawba Rhododendron
Rhododendron catawbiense
Ericaceae · broadleaf evergreen shrub · native
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Catawba rhododendron (Rhododendron catawbiense) is a broadleaf evergreen shrub in the Ericaceae family native to the Allegheny Mountains of the eastern United States. Named for the Catawba River in North Carolina, it reaches 6 ft tall and is notably cold-hardy to -25F. It blooms on previous season's wood.
Catawba rhododendron prefers part shade with acidic soil. It has a significant pest and disease burden with 35 diseases and 21 pests documented. One cultivar is available in the trade. All parts are poisonous to humans, cats, dogs, and horses.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Catawba Rhododendron has reached 'first bloom' (1325 GDD₃₂) and is approaching 'full bloom', predicted around Apr 25.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 23, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,593 | 'Full bloom' | — | — |
| Seattle / UW | 1,554 | 'First bloom' | 'Full bloom' | 26 |
| Kent / Auburn | 1,537 | 'First bloom' | 'Full bloom' | 43 |
| Olympia / Tumwater | 1,505 | 'First bloom' | 'Full bloom' | 76 |
| Bellingham / Whatcom | 1,483 | 'First bloom' | 'Full bloom' | 97 |
| Tacoma / Puyallup | 1,472 | 'First bloom' | 'Full bloom' | 108 |
| Sequim / Rain Shadow | 1,434 | 'First bloom' | 'Full bloom' | 146 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● 'First bloom' BBCH '61' NOW | 1325 | '' |
| ○ 'Full bloom' BBCH '65' NEXT | 1580 | '' est. Apr 25 (forecast) |
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 Apr 23, 2026. Predicted dates use 16-day weather forecast through May 9, 2026, then climate normals.