Enter your ZIP to see whether this is legal to plant in your state, and whether it survives your winter.
Jacob’s-ladder is consistently rated fire resistant by the institutions that assess it.
Six published assessments support its use in fire-resistant landscaping, including extension guidance from Oregon, Washington, Idaho, and Colorado, Idaho field-trial scoring, and FireSmart BC’s compiled plant program. That agreement spans the Willamette Valley, Pacific Northwest, southern Idaho, Colorado’s Rocky Mountain Front Range, and British Columbia.
The numbers fit the recommendations. Idaho Firewise gives Jacob’s-ladder a fire-resistance score of 8 out of 10, within that source’s recommended band of 8 to 10. Colorado State University Extension and the Colorado State Forest Service also print an ignitability score of 8 out of 10. Under their rule, plants scoring 8, 9, or 10 belong in defensible-space zones 1 and 2, so Jacob’s-ladder meets the stated bar. FireSmart BC approves it as a fire-resistant plant, while the extension services include Polemonium among their recommended plants.
Jacob’s-ladder is a perennial in the Polemoniaceae family. Joint guidance from Oregon State, Washington State, and University of Idaho extension services gives it a hardiness range of USDA zones 3a to 8b; Oregon State’s Willamette Valley profile says hardiness varies by species. The conclusion is unusually clear: every assessment favors Jacob’s-ladder, and both numerical scores reach their sources’ recommendation thresholds.
Form
perennial
Rated in
Alaska; British Columbia; Colorado / Rocky Mountain Front Range; Fremont County, Wyoming +4
On this lot
1. Fire evidence and conditions
Fire evidence
Fire-resistant — location does not change the cited classification.
Alaska Division of Forestry opens with the wildfire threat to Alaskans and publishes Alaska firewise-landscape examples. FireApproved publishes 58 exact source owners from its 60 taxon entries and holds the taxon-free fern label. State publication scope does not establish suitability for every Alaska climate, site, or home-ignition-zone placement.
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.
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.
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.
2. Why this plant is relevant here
State distribution
Documented in ID, OR, WA.
Native range
Introduced / established
USDA hardiness
Documented range 3–8.
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.
3–8 explicit range · whole zone precision · source stated
Source taxon: Polemonium spp. · exact match.
Source location: Jacob’s ladder profile, USDA hardiness zones field.
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)
FireSmart BC Plant Program: suitable for HIZ intermediate zone (10-30 m) [FireSmart BC Home Ignition Zone] (with its recommendation)
Fire-resistant Landscape Plants for the Willamette Valley: Jacob's Ladder profile (PDF page 57) [osu-em-9103-profile] (with its recommendation)
Ignition-Resistant Landscape Plants: suitable for defensible-space zones 1-2 (score 8+) [CSU defensible-space zone] (with its recommendation)
Protect Your Home from Wildfire: Ground covers and perennials [Alaska DNR brochure sections] (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.
“Choose the right perennial plants for your fire-resistant landscape”
· original source
The Jacob’s ladder profile prints Polemonium spp.. 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 Polemonium spp. (Jacobs ladder) with the preserved ignitability score.
“Fremont County Firewise Plant List — Polemonium — Jacobs Ladder”
Listed in the source's Ground Covers section; the page describes its listed Firewise plants as generally low-growing, low-debris, and relatively moist.
