arborvitae

Thuja occidentalis · Cupressaceae · all Thuja records · Wikipedia

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Arborvitae has a conflict among its cited rows. The same record documents the traits resinous and dead-material-trap. Those traits remain separate details within the record rather than additional votes in the recommendation conflict.

3 hardiness assertions are kept together under hardiness evidence, where their source details can be compared without folding them into the fire tally. That comparison does not settle the source disagreement. These selected facts apply to Thuja occidentalis. If the disagreement changes the planting choice, related plants supplies cited same-form alternatives while keeping each option's evidence distinct.

Fire-resistant shrubs instead

Form: shrub
Mature height: ~50 ft
Water need: moderate
Rated in: Global; Michigan / Great Lakes; OR; Ohio / Midwest +2

On this lot

1. Fire evidence and conditions

Fire evidence: Mixed evidence — location does not change the cited classification.
Fire-performance conditions
Fire ecology context
Placement evidence: 2 source placement records; source schemes remain separate.
Evidence regions: Global; Michigan / Great Lakes; OR; Ohio / Midwest; Virginia / Mid-Atlantic; eastern US
Maintenance

Typed publication scope: 3 scopes across 3 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.
Virginia Firescapes — Firewise Landscaping for Woodland Homes (430-300) · Official scoped edition
- VA; partial normalized coverage · 2009-04-15
  Virginia Cooperative Extension's publication opens with Virginia wildfire conditions, identifies its Virginia Firewise Landscaping Task Force, and labels plants native to Virginia. FireApproved publishes 306 exact source owners. Publication scope does not establish parcel suitability or current endorsement of this archived 2009 list.

2. Why this plant is relevant here

State distribution: Documented in CT, IA, ID, IL, IN, KY, MA, MD, ME, MI, MN, NC, NH, NJ, NY, OH, OR, PA, RI, SC, TN, VA, VT, WA, WI, WV.
Native range: Current cited native range in CT, IL, IN, KY, MA, MD, ME, MI, MN, NC, NH, NJ, NY, OH, PA, RI, TN, VA, VT, WI, WV.
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.

Current native

21

exact source areas

Current introduced

0

exact source areas

Qualified

0

doubtful or extinct source rows

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

Connecticut (CT)
Illinois (IL)
Indiana (IN)
Kentucky (KY)
Massachusetts (MA)
Maryland (MD)
Maine (ME)
Michigan (MI)
Minnesota (MN)
North Carolina (NC)
New Hampshire (NH)
New Jersey (NJ)
New York (NY)
Ohio (OH)
Pennsylvania (PA)
Rhode I. (RI)
Tennessee (TN)
Virginia (VA)
Vermont (VT)
Wisconsin (WI)
West Virginia (WV)

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-occidentalis · 2016-wayback · as of 2026-08-26

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

Source taxon: Thuja occidentalis · 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 occidentalis · New, January 2007 · as of 2026-08-26

3–7 explicit range · whole zone precision · source stated

Source taxon: Thuja occidentalis · exact match.

Source location: Table 1, tree row.
USDA PLANTS Database — Plant Characteristics · record THOC2 · 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 occidentalis · source identifier match.

Source location: PlantCharacteristics record 15299, 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 (5)

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)”

Commonly used upright landscape evergreen-multi-stem form opens in heavy snow-very susceptable to bagworms.
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”

Requires good drainage; pH adaptive; drought tolerant.
Virginia Firescapes — Firewise Landscaping for Woodland Homes (430-300) — Virginia Cooperative Extension / Virginia Tech (Appleton, Frenzel, Hillegass, Lyons, Steward — Virginia Firewise Landscaping Task Force) · 2009 · original source Primary evidence Expert-curated lineage: ufifas-srs-tree

“H flammability”

Requires good drainage. Not heat tolerant.

Corroboration (2 rows from 2 sources)

Fire-Resistant vs. Highly Flammable Plants — City of Grants Pass · original source Corroboration Compilation lineage: pnw590-tree

“listed highly flammable”
Best Practices for Fire Resistant Landscaping — City of Ashland · original source Corroboration Regulation lineage: pnw590-tree

“listed highly flammable” · original source

Listed without a rating (17)

Corroboration (17 rows from 1 source)

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

17 cited rows from this source; its identity, lineage and tier are stated once.
- Primary study Ganteaume2018: Ganteaume, A. (2018). Does plant flammability differ between leaf and litter bed scale? Role of fuel characteristics and consequences for flammability assessment. International Journal of Wildland Fire, 27, 342-352.
  
  Shared row context: plant part leaves; device epiradiator; site Ganteaume2018-1; sampling summer.
  - Shared measurement context: Ignitability measurement; fuel all; predrying yes.
    - “time to flaming (s): 63.09”
      
      FLAMITS record 3665.
    - “ignition frequency (%): 33.5”
      
      FLAMITS record 3695.
  - “flaming duration (s): 90.86”
    
    FLAMITS record 3680; Sustainability measurement; fuel all; predrying yes.
  - “flame propagation: 0.43”
    
    FLAMITS record 3710; Combustibility measurement; fuel all; predrying yes.
  - Shared measurement context: Ignitability measurement; fuel live; predrying no.
    - “time to flaming (s): 17.37”
      
      FLAMITS record 3725.
    - “ignition frequency (%): 46”
      
      FLAMITS record 3755.
  - “flaming duration (s): 9.36”
    
    FLAMITS record 3740; Sustainability measurement; fuel live; predrying no.
- Primary study Romero2019: Romero, B., Fernandez, C., Lecareux, C., Ormeño, E., & Ganteaume, A. (2019). How terpene content affects fuel flammability of wildlandurban interface vegetation. International Journal of Wildland Fire, 28, 614.
  
  Shared row context: device epiradiator; site Romero2019-1; sampling july.
  - Shared measurement context: Ignitability measurement; plant part litter; fuel dead; predrying yes.
    - “time to flaming (s): 2.6”
      
      FLAMITS record 11334.
    - “temperature at flaming (°C): 351.9”
      
      FLAMITS record 11352.
    - “flammability value: 100”
      
      FLAMITS record 11358.
  - “maximum flame temperature (°C): 612.6”
    
    FLAMITS record 11340; Combustibility measurement; plant part litter; fuel dead; predrying yes.
  - “flaming duration (s): 19.6”
    
    FLAMITS record 11346; Sustainability measurement; plant part litter; fuel dead; predrying yes.
  - Shared measurement context: Ignitability measurement; plant part leaves; fuel live; predrying no.
    - “time to flaming (s): 26.3”
      
      FLAMITS record 11364.
    - “temperature at flaming (°C): 362.3”
      
      FLAMITS record 11386.
    - “flammability value: 87”
      
      FLAMITS record 11393.
  - “maximum flame temperature (°C): 466”
    
    FLAMITS record 11371; Combustibility measurement; plant part leaves; fuel live; predrying no.
  - “flaming duration (s): 18.5”
    
    FLAMITS record 11378; Sustainability measurement; plant part leaves; fuel live; predrying no.

Fire-resistant shrubs instead

black chokeberry
Aronia melanocarpa

common snowberry
Symphoricarpos albus

red elderberry
Sambucus pubens red elderberry
Sambucus racemosa

fragrant sumac
Rhus aromatica

glossy buckthorn
Rhamnus frangula

Fire-resistant shrubs listed above

Guides that discuss this plant

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

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

Thuja occidentalis (Arborvitae). FireApproved. https://fireapproved.com/plants/thuja-occidentalis/. Last verified 2026-08-23.

1. Fire evidence and conditions

2. Why this plant is relevant here

3. Legal, ecological, and broader status

Native and introduced range evidence

21

0

0

Plant hardiness evidence

Where its sources say to plant it

The evidence

Recommends (1)

Avoids (5)

Related plants

Fire-resistant shrubs instead

Guides that discuss this plant