Enter your ZIP to see whether this is legal to plant in your state, and whether it survives your winter.
Yes, Wild Mock Orange is rated fire resistant, but the support is limited and cultivar scores vary.
Idaho Firewise gives its cultivars scores of 7 or 8 out of 10, and the overall verdict reflects the highest-scored form. On that scale, 8 begins the recommended range, while 7 falls into the mixed range.
Colorado State University Extension and the Colorado State Forest Service also give Philadelphus lewisii an ignitability score of 8 out of 10. That score puts the species at Colorado’s minimum for planting in defensible-space zones 1 and 2. This sounds like a second confirmation, but the Colorado fact sheet credits Idaho materials as the basis of its scoring, so the two findings should not be treated as fully separate trials.
About 12 feet tall at maturity, Wild Mock Orange is a low-water shrub in the hydrangea family. It is native to the Southwest and Northwest and hardy to USDA zone 7b. The practical conclusion is favorable but narrow: a cultivar scoring 8 meets both sources’ recommendation threshold, while one scoring 7 does not. For plant selection, the exact cultivar score matters more than the species name alone.
Form
shrub
Mature height
~12 ft
Water need
low
Rated in
Colorado / Rocky Mountain Front Range; southern Idaho / Intermountain
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.
2. Why this plant is relevant here
State distribution
Documented in CA, ID, MT, OR, WA.
Native range
Current cited native range in CA, ID, MT, OR, WA.
Introduced / established
USDA hardiness
Documented minimum 7b; 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.
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 location: PlantCharacteristics record 88455, 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 30' from home [Idaho minimum planting distance] (with its recommendation)
Ignition-Resistant Landscape Plants: suitable for defensible-space zones 1-2 (score 8+) [CSU defensible-space zone] (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.
Cultivar scores span 7-8; verdict reflects the highest-scored form.
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 Philadelphus lewisii (Cheyenne mock orange) with the preserved ignitability score.
