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Tufted evening primrose has mixed fire-resistance evidence, with regional recommendations qualified by Idaho's placement guidance.
The Southern Idaho database gives Oenothera caespitosa a fire-resistance score of seven. Its key associates that score with a suggested minimum distance of forty feet from the home. Idaho names the plant white stemless evening primrose, keeping the placement guidance tied to this botanical identity. Idaho also calls for cutting perennials back in late winter and removing the dead material.
Fremont County includes the same botanical name among its Firewise ground covers. The Black Hills list likewise identifies white stemless evening primrose as a fire-resistive landscaping plant. These are favorable selections without a comparative grade of their own. They therefore add regional support without replacing Idaho's scored placement advice.
Care matters in both lists. Fremont ties Firewise properties to plant choice, spacing and maintenance, while the Black Hills introduction puts maintenance ahead of plant selection and asks gardeners to consider site conditions. For tufted evening primrose, those qualifications make the evidence useful: choose it with the regional planting guidance, retain the Idaho separation where applying that database, and remove the spent perennial growth the source tells gardeners to clear.
Form
perennial
Mature height
~0.5 ft
Water need
low
Rated in
Black Hills, South Dakota; Fremont County, Wyoming; southern Idaho / Intermountain
On this lot
1. Fire evidence and conditions
Fire evidence
Mixed evidence — location does not change the cited classification.
Black Hills (SD footprint); partial normalized coverage
The page explicitly limits itself to the Black Hills, and NFPA Firewise's archived 2006 plant-list index files it under South Dakota. FireApproved publishes 47 exact genus or species owners from 48 printed rows. This is bounded Black Hills context, not statewide South Dakota coverage or a finding that a plant suits a particular site.
Fremont County (WY footprint); partial normalized coverage · 2011-02-25
The source identifies itself as the Fremont County Firewise Plant List. FireApproved publishes its 92 exact source owners as Fremont County regional context. No methodology, current county endorsement, statewide Wyoming scope, or site-specific suitability is inferred.
Southern Idaho (ID footprint); partial normalized coverage · 2013-11-08
The official database labels itself "For Southern Idaho" and describes Idaho residents at the urban-rangeland interface. FireApproved publishes 419 existing plant owners that cite its scored rows. This bounded Southern Idaho scope is regional context, not statewide coverage or a conclusion that the score transfers unchanged to every Idaho site.
2. Why this plant is relevant here
State distribution
Documented in AZ, CA, CO, ID, MT, ND, NE, NM, NV, OR, SD, TX, UT, WA, WY.
Native range
Introduced / established
USDA hardiness
Documented minimum 5b; no upper limit is documented.
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.
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 location: PlantCharacteristics record 86198, 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.
Fire Resistance of Plants Master Database: plantable at 40' from home [Idaho minimum planting distance] (mid-scale rating)
Firewise Plant Material for the Black Hills: Flowers & groundcovers [black-hills-plant-form-table] (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.
“Fremont County Firewise Plant List — Oenothera caespitosa — White Stemless Evening Primrose”
Listed in the source's Ground Covers section; the page describes its listed Firewise plants as generally low-growing, low-debris, and relatively moist.
“Flowers & groundcovers: White stemless evening primrose — Oenothera caespitosa”
The introduction describes all table entries as fire-resistive plants that can be used in landscaping. Printed-name correction used for exact matching: Oenothera caespitosa -> Oenothera cespitosa.
