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Thuja plicata; photograph (c) Daughter Dad, some rights reserved (CC BY) CC BY(c) Daughter Dad, some rights reserved (CC BY) · observed growing wild · 2026-06-25

Thuja plicata Donn ex D.Don

Western red-cedar; Giant arborvitae; Canoe cedar; Giant cedar

Cupressaceae · Alaska, Alberta +6

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Thuja plicata, photograph (c) Daughter Dad, some rights reserved (CC BY)Thuja plicata, photograph (c) Daughter Dad, some rights reserved (CC BY)Thuja plicata, photograph (c) Daughter Dad, some rights reserved (CC BY)Thuja plicata, photograph (c) Sabarni Sarker, some rights reserved (CC BY)Thuja plicata, photograph author not stated, no rights reservedThuja plicata, photograph author not stated, no rights reserved 59 photographs ›
Habitat figures
Cold floor (1 night in 100)
-8.2°C
Record low -20.1 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
23°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,542mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
6–41DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Wet winters: the rain comes October to March, read as a winter growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Thuja plicata is a large coniferous tree in the cypress family, Cupressaceae, native to the Pacific Northwest of North America. Its common name is western redcedar, although it is not a true cedar. It is also less commonly called western red cedar, pacific red cedar, giant arborvitae, western arborvitae, just cedar, giant cedar, or shinglewood. T. plicata is the largest species in the genus Thuja, growing up to 70 metres (230 ft) tall and 7 m (23 ft) in diameter. More on Wikipedia ›

Quoted from Wikipedia, "Thuja plicata", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a winter growing season: 70% of the median year's rain (1,116 mm of 1,538 mm) falls in October to March, cooler than the year (wet-season mean 5.6 °C against a yearly mean of 9.7 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: April to September.

Rain

1,538 mm in the median year at the habitat, 1,116 mm of it October to March. Wettest month November at 237 mm, driest months (2 at 41 mm). Across the grid cells of the range the year's total runs 840 mm to 3,325 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,542 mm, is the year's rain at the top of the page; the 1,538 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 6 to 41 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 4, the highest 90th-percentile month 45).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -8.2 °C, the absolute minimum -20.1 °C, 1,705 frost nights in 44 years, 38.8 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 33.4 °C. Monthly means: the coldest month's mean nightly low 0.7 °C in December (across the grid cells of the range -8.8 °C to 3.8 °C), the warmest month's mean daily high 22.8 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -8.2 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 58 to 66% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected -320 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

Habitat months, northern hemisphere

Habitat climate of Thuja plicata through the yearWarmest months July and August, mean daily high 23 °C; coldest month December, mean nightly low 0.7 °C; 1,538 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-30°-20°-10°0°10°20°30°40°frost33.4° 99th-percentile day, NASA POWER-20.1° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500600mm rainDLI 6–41RH 58–66%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 738 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C6 / -2–87 / 1–109 / 4–1212 / 8–1416 / 12–1819 / 15–2223 / 17–2623 / 18–2719 / 16–2213 / 10–168 / 2–105 / -3–7
Night °C1 / -8–41 / -7–43 / -4–54 / -1–78 / 2–910 / 7–1213 / 10–1513 / 10–1511 / 6–137 / 1–103 / -4–61 / -9–4
Rain mm216 / 97–456148 / 64–322145 / 62–322107 / 51–24687 / 51–16977 / 44–14241 / 19–8941 / 23–10169 / 40–161145 / 71–381237 / 108–503225 / 99–453
DLI7 / 5–813 / 11–1520 / 18–2429 / 27–3436 / 34–4039 / 36–4241 / 38–4536 / 33–3926 / 23–2915 / 12–188 / 6–96 / 4–7
RH %66 / 63–6963 / 61–6562 / 58–6461 / 56–6460 / 55–6460 / 55–6558 / 52–6559 / 52–6660 / 55–6563 / 59–6666 / 64–6965 / 62–69
How this section is made
Each figure is the median across the 738 grid cells on land that hold in-range records (1194 records in those cells; 2 more cells hold records but no land by the elevation layer, so those records sit at sea and the cells are left out), with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 854:1159 (47.275, -122.025). Over 44 years there: absolute minimum -20.1 °C, 1st-percentile night -8.2 °C, 99th-percentile day 33.4 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 738 distinct grid cells holding 1194 of the 1198 in-range records (2 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 854:1159 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 47.50_-121.875, lapse-corrected -320 m at 6.5 °C/km. Elevation: ETOPO 2022, 162 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.
NativeAlaska, Alberta, British Columbia, Idaho, Montana, Oregon, Washington, California · introduced: Denmark, Føroyar, Great Britain, Ireland, Norway, Sweden, Austria, Germany, Poland, Portugal, Spain, Italy · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker48.538, -123.003 · in the densest population, 715 records (57% of those in range)
Kew's description“tree” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1252 georeferenced records inside the native range; the climate across the range on the 1194 of them in the land cells it reads, of 1198 placed to within 10 km; the map shows only the 343 openly licensed ones, which alone would put the marker 54 km away. 332 records outside the WCVP native range not used. 54 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population of the 1252 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Thuja plicata, photograph 1did not loadThuja plicata, photograph 2did not loadThuja plicata, photograph 3did not loadThuja plicata, photograph 4did not loadThuja plicata, photograph 5did not loadThuja plicata, photograph 6did not load

Photographs: (c) Daughter Dad, some rights reserved (CC BY) (3); (c) Sabarni Sarker, some rights reserved (CC BY); author not stated, no rights reserved · CC0 (2).

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Mahonia nervosa Mahonia nervosa Cascade barberry Photo: CC BY, Alina FisherSalix sitchensis Salix sitchensis Sitka willow Photo: CC BY, Sarah MacGregorVaccinium parvifolium Vaccinium parvifolium Red huckleberry Photo: CC BY, Harry PodschwitPolypodium glycyrrhiza Polypodium glycyrrhiza Licorice fern Photo: CC BY, John BrewLysichiton americanus Lysichiton americanus American skunk cabbage Photo: CC BY, EmersonSpiraea douglasii Spiraea douglasii Steeple-bush Photo: CC BY, Gavin Slater

Other Thuja 4 in the reference

Thuja koraiensis Thuja koraiensis Korean arborvitae Photo: CC BY, Drew AveryThuja occidentalis Thuja occidentalis Northern white-cedar Photo: CC0, author not statedThuja standishii Thuja standishii Japanese Arbor-vitae Photo: CC BY, Marco Mussita Thuja sutchuenensis Sichuan Arborvitae

Names & registers

Also known as Libocedrus craigiana; Libocedrus gigantea; Thuja asplenifolia; Thuja californica; Thuja douglasii and 20 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Cupressaceae
Described by
Donn ex D.Don
Native to
Alaska, Alberta, British Columbia +5
Wild records
1252 in range · 343 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-22
GBIF species record gbif.species answeredasked 2026-10-22
GBIF synonyms gbif.synonyms answeredasked 2026-10-22
GBIF common names gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 107 records within 1 km of a botanic garden, herbarium or zoo left out (62 at a botanic garden or arboretum, 17 at a herbarium, 28 at a zoo; Wikidata's list)
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 47.50_-121.875, lapse-corrected -320 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild answeredasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media answeredasked 2026-10-22
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 86 datasets via GBIF.org; each carries its own licence.

Cultifolio

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