Enter your ZIP to see whether this is legal to plant in your state, and whether it survives your winter.
Tree of heaven is not fire resistant: the lab test behind its verdict names it among the highest producers of heat once it burns.
The tree is a Simaroubaceae species that reaches about fifty feet in full sun on moderate water and has been introduced in 45 states. The call that follows from the primary evidence is blunt: highly flammable, keep it away from structures.
That call rests mainly on a cone-calorimeter study in the International Journal of Wildland Fire, which grouped the species, based on its effective heat of combustion, with the taxa its own scale reads as avoid. A Córdoba, Spain ignition-index study reads softer: live foliage measured at nearly 298 percent moisture with a mean time to ignition under ten seconds landed at a score that study's own map calls mixed, not avoid. The U.S. Forest Service's regional Firewise program is softer still, rating the tree Moderately Firewise, the second of four bands, and noting it is very tolerant of inner-city conditions and generally considered a weed.
A Catalan gardening guide from Girona's provincial government and the regional fire brigade rates it prohibida, the bottom of its five bands. That method weighs fuel structure, maintenance and origin alongside fire evidence, and the species is flagged invasive in two jurisdictions, which pulls the score down along with any fire reading. A global flammability-trait database adds one more figure without taking a side: leaves burned at 3,511 kilocalories per kilogram in a calorimeter, describing heat released once a fire is going, not how easily one starts.
The readings do not agree with each other, but the one built from direct combustion testing carries the final call, and the softer scores come from programs built to rank many plants at once rather than to test this one specifically. A tree already considered a weed wherever it takes hold is not a good candidate for an exception near a structure.
Northeastern and mid-Atlantic study sites (ME, MD, MA, NY, VA footprint); partial normalized coverage · 2007-08-20
The authors collected foliage and twigs across study sites in Maine, Maryland, Massachusetts, New York, and Virginia, then conditioned and tested the samples in a cone calorimeter. FireApproved publishes 37 exact source owners only as multi-state laboratory context. The source does not establish that every taxon was sampled in every named state, whole-plant behavior, landscape suitability, or state planting guidance.
2. Why this plant is relevant here
State distribution
Documented in AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MO, MS, NC, NE, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, TN, TX, UT, VA, WA, WI, WV.
Native range
Introduced / established
46 sourced range or established records. This is not an invasive warning.
USDA hardiness
Documented minimum 5a; no upper limit is documented.
3. Legal, ecological, and broader status
Legal-list status
8 legal-list records; the Place chip matches exact scope.
Seed-list status
3 state noxious-weed seed records; the Place chip matches exact scope.
Reported invasive here
2 ecological invasive reports.
Broader regional context
Federal context
Plant-specific legal-list reviews (3)
These source-bound review receipts are separate from ecological invasive reports. A source or plant identity change invalidates a receipt.
IN · Prohibited here. Designated prohibited in the reviewed Indiana 312 IAC 18-3-25 Prohibited Invasive Terrestrial Plants as of 2026-08-26. Authority: Indiana Department of Natural Resources; scope: state; as of 2026-08-26.Official reference.Normalized source record.
OH · Prohibited here. Designated prohibited in the reviewed Ohio OAC 901:5-30-01 Invasive Plant Species as of 2026-08-26. Authority: Ohio Department of Agriculture; scope: state; as of 2026-08-26.Official reference.Normalized source record.
VA · Noxious-listed here. Designated noxious listed in the reviewed Virginia 2VAC5-317 Tier 1, Tier 2, and Tier 3 Noxious Weeds as of 2026-08-26. Authority: Virginia Board of Agriculture and Consumer Services; scope: state; as of 2026-08-26.Official reference.Normalized source record.
Plant-specific state seed-list reviews (1)
These source-bound receipts answer only the July 2026 state noxious-weed seed-list question.
This answers only whether the plant identity appears in the July 2026 state noxious-weed seed sheet. It does not establish non-seed plant legal status, ecological-invasive status, nursery-sale rules, or unrestricted use.
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 4 · single-value meaning unresolved · whole zone precision · source stated
Source taxon: Ailanthus altissima · 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.
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 4 — beyond 30 ft; outside the selector's recommendation area [Fire Performance Plant Selector landscape zone] (mid-scale rating)
Guía de pirojardinería: prohibited as a regulated invasive plant; not a fire-suitability verdict [girona-2020-iuf-25m-suitability] (mid-scale 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.
Ailanthus altissima is rated “PROHIBIDA” by the guide's qualitative IUF garden-suitability method. The method assumes species-specific care and integrates fire evidence with fuel structure, maintenance, origin, invasiveness, and expert fire-service experience.
9 cited rows from this source; its identity, lineage and tier are stated once.
“calorific value (kcal/kg): 3511.03”
FLAMITS record 2858; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site Dibble2007-1; sampling ND. Primary study Dibble2007: Dibble, A. C., White, R. H., & Lebow, P. K. (2007). Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter: invasive versus non-invasive plants. International journal of wildland fire, 16, 426-443.
Primary study Molina2017: Molina, J. R., Martín, T., Rodríguez Y Silva, F., & Herrera, M. Á. (2017). The ignition index based on flammability of vegetation improves planning in the wildland-urban interface: A case study in Southern Spain. Landscape and Urban Planning, 158, 129-138.
Shared row context: plant part leaves; fuel live; predrying no; device epiradiator; site Molina2017-1; sampling summer.
Primary study Molina2019: Molina, J., Lora, A., Prades, C., & Silva, F. R. (2019). Roadside vegetation planning and conservation: New approach to prevent and mitigate wildfires based on fire ignition potential. Forest ecology and management, 444, 163-173.
Shared row context: plant part leaves; fuel live; predrying no; device epiradiator; site Molina2019-1; sampling july and september.
FLAMITS record 13727; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site Wang2009-1; sampling november. Primary study Wang2009: Wang, X., Niu, S., & Kan, Z. (2009). Properties and flammability of major tree species in the Beijing area. Frontiers of Forestry in China, 4, 304-308.
