Home / Plants / Grow / Western arborvitae

Western arborvitae

Thuja plicata · Cupressaceae · all Thuja records

Your local evidence lens

Separate evidence questions, never one approval badge

Set a ZIP to compare this record with state distribution, native range, USDA hardiness, and invasive records.

A genus split is not a placement verdict. Set a ZIP to read the local documented split.

1. Fire evidence and conditions

Fire evidence: Mixed evidence — location does not change the cited classification.
Fire-performance conditions: No test or rating condition is normalized.
Fire ecology context: No section-reviewed fire-ecology context is normalized.
Placement evidence: 2 source placement records; source schemes remain separate.
Evidence regions: Global; Michigan / Great Lakes; Ohio / Midwest; eastern US
Maintenance: No sourced horticultural maintenance assertion is normalized; fire-test conditions do not supply maintenance advice.

Typed publication scope: 2 scopes across 2 cited fire sources

Wildfire-resistant Landscape Plants for Michigan (Extension Bulletin E2948) · Official scoped edition
- MI; partial normalized coverage · 2007-01-01
  Michigan State University Extension Bulletin E2948 is explicitly a list of wildfire-resistant landscape plants for Michigan and includes a Michigan-native field. FireApproved publishes 221 exact GBIF owners from 226 represented source rows and holds 15 complex or non-exact rows. This dated publication scope is not a current site-suitability determination.
Firewise Landscaping (OSU Extension Bulletin 921) · Official scoped edition
- OH; partial normalized coverage · 2006-03-01
  Ohio State University Extension Bulletin 921 is an Ohio publication that describes Ohio fire seasons and landscape conditions and labels nativity to Ohio. FireApproved publishes 352 exact source-owning plant records from its eight rated tables. This historical publication scope does not assert current extension endorsement or that a listed plant suits every Ohio site.

2. Why this plant is relevant here

State distribution: Documented in AK, CA, DC, DE, ID, MD, MT, NJ, OH, OR, PA, WA, WV.
Native range: Current cited native range in AK, CA, ID, MT, OR, WA.
Introduced / established: No introduced or established row is normalized; that does not prove native status.
USDA hardiness: 2 applicable cited hardiness statements overlap but have different boundaries; compare each complete source row.

3. Legal, ecological, and broader status

Legal-list status: Set a location for an exact legal-list result; source silence is not clearance.
Seed-list status: Set a location to compare the separate state noxious-weed seed layer.
Reported invasive here: No ecological invasive report is normalized; that does not prove noninvasiveness.
Broader regional context: Aggregate AK, HI, and L48 evidence is shown only as regional context, never as an exact-state finding.
Federal context: Federal designations remain separate from state legal-list results.

How to read this page

The status above is computed from the cited rows below: independent recommendations can support a fire-resistant result, an avoid row can produce keep-away, and disagreement stays visible as conflict. Placement notes preserve each source’s own scheme rather than translating unlike rules into one scale. This is evidence about a plant, not permission to plant it in every part of the defensible space; Zone 0 remains noncombustible.

Western arborvitae (Thuja plicata) — Photo: no rights reserved (CC0), via iNaturalist. Species-typical, not necessarily this cultivar.

Form: tree
USDA hardiness: Applicable source statements overlap but have different boundaries; compare each source
Mature height: ~100 ft
Light: Full sun
Water need: moderate
Current cited native range: AK, CA, ID, MT, OR, WA
Grows in: AK, CA, DC, DE, ID, MD, MT, NJ +5
Rated in: Global; Michigan / Great Lakes; Ohio / Midwest; eastern US
Family: Cupressaceae
Evidence: 19 cited sources

Native and introduced range evidence

These are exact U.S. botanical-area records from the cited range source. Native and introduced describe biogeographic relationship, not fire performance or planting approval. Doubtful and extinct rows stay visible but do not count as current presence.

Current native

6

exact source areas

Current introduced

0

exact source areas

Qualified

0

doubtful or extinct source rows

6 native source areas · World Checklist of Vascular Plants, version 16 v16, as of 2026-06-04

Alaska (AK)
California (CA)
Idaho (ID)
Montana (MT)
Oregon (OR)
Washington (WA)

The lossless worldwide derivative is retained once in the research corpus; object pages repeat only exact U.S. areas needed by the local lens. The JSON twin carries the same page assertions.

Plant hardiness evidence

These values describe the plant source. Your ZIP zone comes from the separate 2023 USDA Plant Hardiness Zone Map. Whole-zone values stay whole-zone, and a single unresolved value is not treated as a tolerance range. Different source boundaries stay separate: overlapping statements are compared independently, while only ranges with no shared zone are called a conflict.

Eastern United States Fire Performance Plant Selector · record thuja-plicata · 2016-wayback · as of 2026-08-26

Source prints 5 · single-value meaning unresolved · whole zone precision · source stated

Source taxon: Thuja plicata · exact match.

Source location: Cold Hardiness Zone field in the recovered selector record.

Not used for comparison: The recovered selector prints one Cold Hardiness Zone value but does not define it as a minimum threshold or a one-zone range.
Wildfire-resistant Landscape Plants for Michigan (Extension Bulletin E2948) · record tree:Thuja plicata · New, January 2007 · as of 2026-08-26

5–7 explicit range · whole zone precision · source stated

Source taxon: Thuja plicata · exact match.

Source location: Table 1, tree row.
USDA PLANTS Database — Plant Characteristics · record THPL · PLANTS Help Document 2022; characteristics cache retrieved 2026-08-23 · as of 2026-08-26

Minimum 3b · no upper limit documented · half zone precision · derived containing band

Exact source measurement: -33°F; mapped only to its containing half-zone.

Source taxon: Thuja plicata · source identifier match.

Source location: PlantCharacteristics record 15304, Temperature, Minimum (°F).

Where its sources say to plant it

Placement rules below use each source's own distances or named zones, tied to its rating. They are not interchangeable with the directory's current Zone 0 guidance.

Eastern United States Fire Performance Plant Selector: Landscape Zone 3 — 10–30 ft from the structure; thin vegetation, remove debris, and minimize plant massing [Fire Performance Plant Selector landscape zone] (with its avoid rating)
Firewise Landscaping: keep 30 ft from the home (Zone 3) [OSU B921 source-category siting] (with its avoid rating)

The evidence

Grouped by what each source concluded. Primary evidence rated the plant itself (a lab, field program, or original curation); corroboration compiled or republished another source's rating and resolves to its root lineage.

Avoids (2)

Eastern United States Fire Performance Plant Selector — USDA Forest Service Northeastern Area S&PF + state Firewise programs (WV, OH, PA, DE, DC, MD, NJ) · 2016-wayback · original source Primary evidence Keyed curation lineage: ufifas-srs-tree

“NOT Firewise (4)”

Fast growing screen in hot, dry, sunny locations. Excellent tall screen. Deer will eat lower branches in winter.
Firewise Landscaping (OSU Extension Bulletin 921) — Ohio State University Extension (Sydnor, Steward, Kloss / Ohio DNR Division of Forestry) · 2006 · original source Primary evidence Expert-curated lineage: ufifas-srs-tree

“H flammability”

Reported to have some deer resistance; adapts to urban sites; fast growth.

Listed without a rating (16)

FLAMITS: FLAMmability plant traiTS database — Dryad / Global Ecology and Biogeography · Dryad version 9 · original source Corroboration Trait database lineage: meta-aggregator

16 cited rows from this source; its identity, lineage and tier are stated once.
- “calorific value (kcal/kg): 4815.13” · score 4815.13 (FLAMITS — calorific value (kcal/kg))
  
  FLAMITS record 5655; Combustibility measurement; plant part bark; fuel all; predrying yes; device calorimeter; site Kelsey1979-1; sampling ND. Primary study Kelsey1979: Kelsey, R. G., Shafizadeh, F., & Lowery, D. P. (1979). Heat content of bark, twigs, and foliage of nine species of western conifers. United States Department of Agriculture, Forest Service, Research Paper INT-261. Intermountain Forest and Range Experiment Station, Ogden, Utah.
- “calorific value (kcal/kg): 4839.01” · score 4839.01 (FLAMITS — calorific value (kcal/kg))
  
  FLAMITS record 5656; Combustibility measurement; plant part twigs; fuel all; predrying yes; device calorimeter; site Kelsey1979-1; sampling ND. Primary study Kelsey1979: Kelsey, R. G., Shafizadeh, F., & Lowery, D. P. (1979). Heat content of bark, twigs, and foliage of nine species of western conifers. United States Department of Agriculture, Forest Service, Research Paper INT-261. Intermountain Forest and Range Experiment Station, Ogden, Utah.
- “calorific value (kcal/kg): 5350.14” · score 5350.14 (FLAMITS — calorific value (kcal/kg))
  
  FLAMITS record 5657; Combustibility measurement; plant part leaves; fuel all; predrying yes; device calorimeter; site Kelsey1979-1; sampling ND. Primary study Kelsey1979: Kelsey, R. G., Shafizadeh, F., & Lowery, D. P. (1979). Heat content of bark, twigs, and foliage of nine species of western conifers. United States Department of Agriculture, Forest Service, Research Paper INT-261. Intermountain Forest and Range Experiment Station, Ogden, Utah.
- “time to flaming (s): 5.4” · score 5.4 (FLAMITS — time to flaming (s))
  
  FLAMITS record 16480; Ignitability measurement; plant part leaves; fuel live; predrying no; device flat flame burner; site Fazeli2022-1; sampling september to february. Primary study Fazeli2022: Fazeli, H., Jolly, W. M., & Blunck, D. L. (2022). Stages and time-scales of ignition and burning of live fuels for different convective heat fluxes. Fuel, 324, 124490.
- “time to flaming (s): 20.8” · score 20.8 (FLAMITS — time to flaming (s))
  
  FLAMITS record 16481; Ignitability measurement; plant part leaves; fuel live; predrying no; device flat flame burner; site Fazeli2022-1; sampling september to february. Primary study Fazeli2022: Fazeli, H., Jolly, W. M., & Blunck, D. L. (2022). Stages and time-scales of ignition and burning of live fuels for different convective heat fluxes. Fuel, 324, 124490.
- “time to flaming (s): 0.4” · score 0.4 (FLAMITS — time to flaming (s))
  
  FLAMITS record 16482; Ignitability measurement; plant part leaves; fuel dead; predrying no; device flat flame burner; site Fazeli2022-1; sampling september to february. Primary study Fazeli2022: Fazeli, H., Jolly, W. M., & Blunck, D. L. (2022). Stages and time-scales of ignition and burning of live fuels for different convective heat fluxes. Fuel, 324, 124490.
- “time to flaming (s): 3.7” · score 3.7 (FLAMITS — time to flaming (s))
  
  FLAMITS record 16483; Ignitability measurement; plant part leaves; fuel dead; predrying no; device flat flame burner; site Fazeli2022-1; sampling september to february. Primary study Fazeli2022: Fazeli, H., Jolly, W. M., & Blunck, D. L. (2022). Stages and time-scales of ignition and burning of live fuels for different convective heat fluxes. Fuel, 324, 124490.
- “time to flaming (s): 725” · score 725 (FLAMITS — time to flaming (s))
  
  FLAMITS record 19131; Ignitability measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “time to flaming (s): 50” · score 50 (FLAMITS — time to flaming (s))
  
  FLAMITS record 19132; Ignitability measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “time to flaming (s): 20” · score 20 (FLAMITS — time to flaming (s))
  
  FLAMITS record 19133; Ignitability measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “energy flux (kW/m²): 98.1” · score 98.1 (FLAMITS — energy flux (kW/m²))
  
  FLAMITS record 19140; Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “energy flux (kW/m²): 126.9” · score 126.9 (FLAMITS — energy flux (kW/m²))
  
  FLAMITS record 19141; Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “energy flux (kW/m²): 186” · score 186 (FLAMITS — energy flux (kW/m²))
  
  FLAMITS record 19142; Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “mass loss rate (g/s): 0.02” · score 0.02 (FLAMITS — mass loss rate (g/s))
  
  FLAMITS record 19149; Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “mass loss rate (g/s): 0.06” · score 0.06 (FLAMITS — mass loss rate (g/s))
  
  FLAMITS record 19150; Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
- “mass loss rate (g/s): 0.07” · score 0.07 (FLAMITS — mass loss rate (g/s))
  
  FLAMITS record 19151; Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND. Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.

Fire-resistant trees instead

Quaking aspen
Populus tremuloides

Boxelder
Acer negundo

Thornless honeylocust
Gleditsia triacanthos

Smooth sumac
Rhus glabra

Paper birch
Betula papyrifera

American sweetgum
Liquidambar styraciflua

Fire-resistant trees listed above

Last verified 2026-08-23. JSON (CC BY 4.0)

Profiles: USDA PLANTS · GBIF · iNaturalist · Wikidata · ITIS

Thuja plicata (Western arborvitae). FireApproved. https://fireapproved.com/plants/thuja-plicata/. Last verified 2026-08-23.