Enter your ZIP to see whether this is legal to plant in your state, and whether it survives your winter.
Common rock-rose is consistently rated fire resistant by six authorities.
The strongest numerical support comes from Idaho Firewise, whose field-trial database gives the plant 8 of 10. CSU’s published usage of this scale places scores of 8 to 10 in the recommended band. The joint extension services of Oregon State, Washington State and the University of Idaho also list it as fire resistant, as do Washington State’s natural-resources department and Anaheim Fire & Rescue. FireSmart BC approves it as a fire-resistant plant.
The support combines field-trial findings with expert-curated and compiled recommendations. The recommendations extend from Southern California through the inland Northwest to British Columbia. The University of Nevada’s compilation adds another check: it includes plants reported favorably by at least two of seven named western sources, and common rock-rose meets that standard without the caution mark used for disputed choices.
Common rock-rose is a perennial in the Cistaceae family. The joint extension listing gives it a hardiness span of USDA zones 4a to 7b. Its fire-resistant rating is therefore well supported as a planting recommendation, though the phrase should not be mistaken for an inability to burn.
Form
perennial
Rated in
British Columbia; California; Colorado / Rocky Mountain Front Range; Michigan / Great Lakes +9
On this lot
1. Fire evidence and conditions
Fire evidence
Fire-resistant — location does not change the cited classification.
Colorado State University Extension and the Colorado State Forest Service publish Fact Sheet 6.305 for Colorado's WUI and varied ecosystems. FireApproved exposes all 114 exact source owners at Colorado publication scope while retaining score, elevation, water, and Idaho-carrier lineage. Publication scope is not suitability for every Colorado site or zone.
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.
The UC Forest Products Laboratory says the guide covers properties of common California landscaping plants and was prepared for California fire agencies. FireApproved publishes 130 exact owners at historical California publication scope. The report is a 1997 compilation, not a current endorsement, site rating, or independent test of every row.
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.
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.
The October 2023 joint Pacific Northwest Extension publication explicitly names Oregon, Washington, and Idaho and publishes more than 150 plant profiles. FireApproved has normalized 155 exact plant records from the source; publication scope does not assert that every listed plant suits every site within the three states.
University of Nevada Cooperative Extension compiled plants suited to Nevada climate zones and reported favorably by at least two upstream firewise lists. FireApproved publishes 126 exact source owners at Nevada publication scope. The source explicitly makes no independent flammability determination, so these rows remain corroborative.
Eastern Washington (WA footprint); partial normalized coverage
Washington DNR publishes the guide for Eastern Washington and says it compiles plants from other Firewise documents that are likely to thrive there. FireApproved publishes 46 exact owners only as eastern Washington context. The rows are corroborative, not empirical or statewide.
2. Why this plant is relevant here
State distribution
Documented in ID, OR, WA.
Native range
Introduced / established
USDA hardiness
3 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.
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.
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 30' from home [Idaho minimum planting distance] (with its recommendation)
FireSmart BC Plant Program: suitable for HIZ intermediate zone (10-30 m) [FireSmart BC Home Ignition Zone] (with its recommendation)
Fire-Retardant Plants for Brush Fire Prevention in Hillsi…: Category 4 [la-arboretum-1970-leaf-moisture-fire-retardance] (with its recommendation)
Landscape for Fire Protection: irrigated hillsides [maire-1968-fire-protection-landscape] (with its recommendation)
Fire-Resistant Plants for Oregon Home Landscapes: Oregon [osu-frn6-oregon-regions] (with its recommendation)
Fire-resistant Landscape Plants for the Willamette Valley: Sun Rose profile (PDF page 95) [osu-em-9103-profile] (with its recommendation)
Fire-resistant plant profile galleries: Sun rose — Helianthemum nummularium [osu-2023-perennials-gallery] (with its recommendation)
Ignition-Resistant Landscape Plants: suitable for defensible-space zones 1-2 (score 8+) [CSU defensible-space zone] (with its recommendation)
Defensible Space Landscaping in the Urban/Wildland Interf…: Chapter 4, Landscape Vegetation Database [ucfpl-1997] (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.
“CATEGORY 4 — LEAST FIRE RETARDANCE Plants with medium leaf moisture content capacity (60-70%)”
· condition: green
Helianthemum nummularium (Sunrose) is one of 30 low-growing plants in the source's recommended Table 1. The category reflects leaf moisture capacity under normal garden conditions at the Arboretum.
Helianthemum nummularium (Sunrose) appears in the source's conditioned examples for landscaping irrigated hillsides. Fuel volume is to be minimized, plants watered to their needs, and accumulated litter removed.
“Fire-Resistant Plant Materials for Oregon”
· condition: green
Helianthemum nummularium (Sun rose) is listed under “Perennials 18 inches or taller”. The guide says most listed plants require some irrigation during Oregon's dry summer months and must be maintained in a healthy condition.
“Choose the right perennial plants for your fire-resistant landscape”
· original source
The Sun rose profile prints Helianthemum nummularium. The gallery points to PNW 590 for complete details.
Ignition-Resistant Landscape Plants (Fact Sheet 6.305) — Colorado State University Extension / Colorado State Forest Service (Wildfire Mitigation Series) · 2025 · original sourcePrimary evidenceField programlineage: idaho-tree resolves to Fire Resistance of Plants Master Database
“ignitability score 8 of 10”
· score 8 (idaho-0-10)
CSU 6.305 table lists Helianthemum nummularium (rockrose, sunrose) with the preserved ignitability score.
