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Four o'clock is rated fire resistant by two university extension services.
Montana State University Extension lists Mirabilis species among fire-resistant plants adapted to Montana. Oregon State University Extension also recommends four o'clock, placing it among fire-resistant plants suited to Willamette Valley growing conditions. Its profile adds that USDA hardiness zones vary by species. These are regional landscape recommendations, not laboratory measurements, but both institutions put the genus on the fire-resistant side of their binary lists.
The agreement is useful because the recommendations come from different growing regions. It does not erase local conditions: Montana’s finding concerns plants adapted to Montana, while Oregon’s applies to the Willamette Valley. Nor does the shared genus name mean every species has the same cold tolerance, as Oregon’s variable hardiness note makes clear.
Four o'clock is a perennial in the Nyctaginaceae family. For a homeowner considering it as part of a fire-resistant planting plan, the evidence supports the choice, provided the particular species is suited to the site’s climate.
The April 2022 MontGuide explicitly presents fire-resistant species adapted to Montana. FireApproved publishes 92 exact plant records from the source while retaining excluded genus, family, and unresolved rows; the guide itself says not every listed species grows in every part of the state.
Willamette Valley (OR footprint); partial normalized coverage · 2015-02-01
OSU Extension says EM 9103 highlights fire-resistant plants that thrive under Willamette Valley growing conditions. FireApproved publishes 172 exact owners only as valley context. The guide shares the PNW 590 lineage and is not a second independent vote or statewide site clearance.
2. Why this plant is relevant here
State distribution
Documented in MT.
Native range
Introduced / established
USDA hardiness
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.
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.
Fire-resistant Landscape Plants for the Willamette Valley: Four O’clock profile (PDF page 12) [osu-em-9103-profile] (with its recommendation)
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.
