Illustration
Western Red Cedar
Thuja plicata
Also called giant arborvitae and western redcedar
Western Red Cedar is grown for its foliage rather than flowers, giving the garden structure and color all season long.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Western Red Cedar
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–7. Expect it to reach about 60 ft tall and 20 ft wide at maturity, in roughly 12 years (a house reading).
Is Western Red Cedar toxic to dogs or cats?
- Listed as toxic to dogs and cats by University of California Agriculture and Natural Resources.
- Listed as poisonous to people by Royal Horticultural Society.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Western Red Cedar
Plant Western Red Cedar in spring once the soil is workable, or by very early fall at the latest: an evergreen needs its roots down well before the ground freezes. In zone 6, the middle of its hardy zones 5 to 7, that is March to May, or August on the fall side.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Western Red Cedar get?
60 fttall5 ft 7 inan adult20 ftwideSee Western Red Cedar in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Western Red Cedar
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Give Western Red Cedar about 20 ft of clear ground in every direction, measured from its center. It is one plant with room around it, not a row, and a raised bed is too small for it.
Add Western Red Cedar to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Western Red Cedar's height, spread, hardiness zones, sun, water and trait tags were checked against 8 published sources on October 23, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources. Bloom was checked as well: Western Red Cedar bears no flowers, so there is no bloom window for a source to carry.
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water and trait tags
- plantdatabase.uconn.eduUniversity of Connecticut, Plant Database (Mark H. Brand)height, spread, hardiness zones, sun, water and trait tags
- NC State ExtensionPlant Toolboxheight, spread, hardiness zones, sun and water
- woodyplants.cals.cornell.eduCornell University, Woody Plants Databaseheight, spread, hardiness zones, sun and water
- himanursery.comHima Nurseryheight, spread, sun and water
- Oregon State UniversityLandscape Plantsheight, hardiness zones, sun and water
- RHSRoyal Horticultural Societyheight, sun and water
- dendro.cnre.vt.eduVirginia Tech Dendrologyheight
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
Native to 6 states and 2 provinces
United States: Alaska, California, Idaho, Montana, Oregon, Washington
Canada: Alberta, British Columbia
Recorded growing wild in 66 counties.
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.