Enter your ZIP to see whether this is legal to plant in your state, and whether it survives your winter.
Red alder is rated fire resistant, but one Firewise source calls it at risk and the overall support is limited.
Pacific Northwest university extensions and FireSmart BC recommend it. Oregon State includes red alder among fire-resistant deciduous trees for Southern and Western Oregon, while advising that most plants in that guide need some irrigation during Oregon’s dry summer months and must be kept healthy. That condition fits a tree described as needing high water. Red alder is native to western and subarctic North America and is listed for USDA zones 5a through 8b.
The disagreement comes from sources using different systems. The eastern United States Firewise selector gives red alder a rating of 3 on its four-point scale, meaning “At Risk,” and tells growers to plant it in wet land areas. Idaho Firewise also prints a value of 70, but its stated fire-resistance scale runs from 0 to 10, so that unexplained number cannot clarify the choice.
For a homeowner, the regional recommendations support treating a healthy, adequately watered red alder as fire resistant, not fireproof. Its mature height of about 90 feet also makes placement and maintenance consequential. The resistant verdict is reasonable for the Pacific Northwest conditions behind the recommendations, but the conflicting Firewise rating leaves less certainty outside those conditions.
Form
tree
Mature height
~90 ft
Water need
high
Rated in
British Columbia; OR/WA/ID; Oregon; Pacific Northwest (Oregon / Washington / Idaho) +2
On this lot
1. Fire evidence and conditions
Fire evidence
Fire-resistant — location does not change the cited classification.
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 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 AK, CA, ID, MT, OR, WA.
Native range
Current cited native range in AK, CA, ID, MT, OR, WA.
Introduced / established
USDA hardiness
2 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.
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 prints 6 · single-value meaning unresolved · whole zone precision · source stated
Source taxon: Alnus rubra · exact match.
Source location: Cold Hardiness Zone field in the recovered selector record.
Not used for comparison: The recovered selector prints one Cold Hardiness Zone value but does not define it as a minimum threshold or a one-zone range.
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.
Eastern United States Fire Performance Plant Selector: Landscape Zone 3 — 10–30 ft from the structure; thin vegetation, remove debris, and minimize plant massing [Fire Performance Plant Selector landscape zone] (mid-scale rating)
FireSmart BC Plant Program: suitable for HIZ extended zone and beyond [FireSmart BC Home Ignition Zone] (with its recommendation)
Fire-Resistant Plants for Oregon Home Landscapes: Southern and Western Oregon [osu-frn6-oregon-regions] (with its recommendation)
Fire-resistant plant profile galleries: Red alder — Alnus rubra [osu-2023-trees-gallery] (with its recommendation)
Fire Resistance of Plants Master Database: 70 ft minimum planting distance on flat terrain [Idaho minimum planting distance] (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.
“Fire-Resistant Plant Materials for Oregon”
· condition: green
Alnus rubra (Red alder) is listed under “Trees—deciduous” for Southern and Western Oregon. The guide says most listed plants require some irrigation during Oregon's dry summer months and must be maintained in a healthy condition.
