Enter your ZIP to see whether this is legal to plant in your state, and whether it survives your winter.
Western arborvitae is shown with a conflict across its evidence rows. The record also contains 3 hardiness assertions under hardiness evidence. Those assertions describe climatic scope on this page and do not add positions to the fire disagreement for this species.
This page keeps the conflicting source rows visible for Thuja plicata instead of choosing between them. If that disagreement makes western arborvitae a poor fit for the intended planting, related plants supplies cited same-form alternatives. Their evidence remains on their own records rather than being inferred from this species.
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.
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
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
Seed-list status
Reported invasive here
Broader regional context
Federal context
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.
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.
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.
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.
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.
16 cited rows from this source; its identity, lineage and tier are stated once.
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.
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.
Shared row context: Ignitability measurement; plant part leaves; predrying no; device flat flame burner; site Fazeli2022-1; sampling september to february.
Shared measurement context: fuel live.
“time to flaming (s): 5.4”
FLAMITS record 16480.
“time to flaming (s): 20.8”
FLAMITS record 16481.
Shared measurement context: fuel dead.
“time to flaming (s): 0.4”
FLAMITS record 16482.
“time to flaming (s): 3.7”
FLAMITS record 16483.
Primary study Hao2020: Hao, H., Chow, C. L., & Lau, D. (2020). Effect of heat flux on combustion of different wood species. Fuel, 278, 118325.
Shared row context: plant part wood; fuel dead; predrying yes; device calorimeter; site Hao2020-1; sampling ND.
