Western Redcedar
Thuja plicata
Cupressaceae · coniferous tree · native
Last updated
Western redcedar is the backbone of Puget Sound lowland forests and the single best large evergreen for this region. It tolerates a wide range of lowland soils including glacial till and alluvial clay, thrives in wet winters, and handles shade better than any other native conifer of comparable size. The catch is summer drought: established redcedars in the I-5 corridor have been showing crown dieback after consecutive dry summers, and young trees planted in exposed sites without irrigation will struggle July through September. Leaf blight (Keithia) is the most common disease, mainly cosmetic on mature trees but capable of killing nursery stock. Yellow root rot moves through root contact in stressed trees. Water deeply through the first three dry seasons and mulch generously. Once established, this tree essentially takes care of itself.
— Chris Welch, ISA Certified Arborist
Western redcedar is a native conifer of western North America, reaching 150 ft with a conical form and fine foliage texture. It has brown cones, yellow flowers, and is valued for its aromatic, durable wood. The bark is thin, layered, and historically was stripped for textiles.
Western redcedar prefers sun to part shade with moist soil and high moisture (pH 4.5-7.0) in zones 5a-8b. It grows at a moderate rate and is long-lived with low maintenance once established. It tolerates clay and black walnut and is useful in hedges and rain gardens.
Quick Facts
Phenological Calendar
| Stage | Typical Window |
|---|---|
| New growth flush BBCH 11 | Feb 15-Mar 15 |
| Bloom start BBCH 61 | Apr 1-Apr 30 |
| 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 |