Eastern Arborvitae
New growth flushThuja occidentalis
Cupressaceae · coniferous tree · native
Last updated
Eastern arborvitae (American arborvitae) is a conifer native to eastern and central North America. It reaches 40 ft with a conical form, fine foliage texture, and brown cones. It has reddish-brown bark fissured into narrow ridges and grows as a single-stem tree.
Eastern arborvitae is hardy in zones 4a-9b and tolerates sun to part shade with wet-tolerant, alkaline soils (pH 5.2-7.0). It grows slowly with low maintenance and is notably tolerant of clay, wet soil, and urban conditions. The essential oil in foliage is poisonous if ingested in large doses.
Quick Facts
Spring Spore Release
Crawler Emergence
Growing Season Stress Expression
Adult Emergence & Egg Laying
+ 1 more — see full disease and pest lists below
Field Observations
Phenological Calendar
As of May 13, 2026, Puget Sound stations range from 1906.2 to 2098.2 GDD₃₂. Eastern Arborvitae has passed new growth flush (1596 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 13, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,098 | New growth flush | — | — |
| Kent / Auburn | 2,089 | New growth flush | — | — |
| Seattle / UW | 2,063 | New growth flush | — | — |
| Olympia / Tumwater | 2,025 | New growth flush | — | — |
| Tacoma / Puyallup | 1,993 | New growth flush | — | — |
| Bellingham / Whatcom | 1,972 | New growth flush | — | — |
| Sequim / Rain Shadow | 1,906 | New growth flush | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● New growth flush BBCH 11 NOW | 1596 | Feb 15-Mar 15 |
| Pollen release BBCH 61 | — | Apr 1-Apr 30 |
| Pollen shed complete BBCH 69 | — | Apr 15-May 15 |
| Cone development BBCH 71 | — | Jun 1-Aug 31 |
| Cone maturity and seed shed BBCH 85 | — | Sep 1-Nov 30 |
Source: Field observation, Issaquah, WA, 2026-04-23 About GDD₃₂ →
Season tracker for Kent / Auburn as of May 13, 2026. Predicted dates use 16-day weather forecast through May 29, 2026, then climate normals.