Generally — Most Areas
Atlantic white cedar (zones 4-8) suits most of Idaho (3b-8a) — zones 4-8 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Idaho spans zones 3b-8a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score atlantic white cedar against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Atlantic White Cedar Needs
- USDA Zones: 4-8
- Frost-Free Days: 140+
- Sun: Part Sun
- Mature size: 50 ft tall
- Drought tolerance: Low
Idaho Has
- USDA Zones: 3b-8a
- Last Hard Freeze (28°F): Apr 26 - May 17
- First Hard Freeze (28°F): Oct 1 - Oct 17
- Annual Rainfall: 8-35 inches
- Common Soils: Volcanic ash, Silt loam, Sandy loam
Plant Zone Range (zones 4-8)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Atlantic White Cedar in Idaho
The frost window
Across Idaho, the last spring hard freeze (28°F) clears between Apr 26 and May 17, and the first fall hard freeze lands between Oct 1 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 137-day window you can count on — up to 174 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Winter standing
Idaho runs as cold as USDA zone 3, and no sourced winter-hardiness floor is on record for atlantic white cedar, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether atlantic white cedar is a permanent planting or a replant-every-spring crop for you turns on your own zone within Idaho; check its hardiness range against that before treating it as long-lived ground.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says atlantic white cedar survives winter in part of Idaho, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Atlantic White Cedar wants 140+ frost-free days; a typical Idaho site sees ~160 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Atlantic White Cedar prefers acidic soil (pH 3.5-5.5). Idaho's volcanic ash can run on the acidic side, which often aligns well — confirm with a soil test before planting. It will grow across that whole span, but it does best between pH 4 and 5.5 — worth knowing before you decide whether a Idaho soil test result is a problem or just a number. Drainage requirement: poorly (saturated >50% of year). A soil-survey lookup (NRCS SSURGO) flags whether your specific site matches.
Plant pH and drainage requirements from USDA PLANTS Database. Idaho soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Atlantic White Cedar in Idaho — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 4-8 (USDA PLANTS Database)
- State Zones: 3b-8a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 26 - May 17 to Oct 1 - Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Atlantic White Cedar in Idaho
Zone compatibility tells you about winter cold survival — but Idaho growers also need to think about:
Short growing season at higher elevations
Arid conditions require irrigation in most of the state
Cold winter snaps can reach -30F in mountain valleys
What to actually do about these — and the constraints that apply to every Idaho grower, not just atlantic white cedar — is covered on the Idaho growing guide.
Timing shifts within Idaho
Atlantic White Cedar needs about 140 days of frost-free season to complete its cycle. 30 of Idaho’s 44 counties give it that outright. The tightest that does is Clark County at 142 frost-free days — 2 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Idaho’s 44 counties the frost-free season runs from 94 days in Valley County to 216 days in Nez Perce County — a spread of 122 days, which is why a single statewide planting date misleads. The median Idaho county sees 160 frost-free days, leaving atlantic white cedar about 20 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Atlantic White Cedar's 140-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Where in Idaho Fits Best
Even within Idaho's zones 3b-8a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for atlantic white cedar (USDA PHZM 2023):
Idaho Cooperative Extension
For Idaho-specific cultivar recommendations, planting calendars, and pest pressure for atlantic white cedar, the canonical source is University of Idaho Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Atlantic White Cedar native to Idaho?
Atlantic White Cedar is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Idaho. It can still earn a place in a Idaho garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The Idaho growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Atlantic White Cedar in Idaho
When can I plant Atlantic White Cedar in Idaho?
Idaho's last spring hard freeze (28°F) clears between Apr 26 and May 17, and the first fall hard freeze lands between Oct 1 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Atlantic White Cedar, so this page does not state whether it overwinters in Idaho and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Atlantic White Cedar grown in across Idaho?
Idaho spans USDA hardiness zones 3b-8a (USDA ARS PHZM 2023). Atlantic White Cedar carries a range of zones 4-8, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Idaho site have?
A typical Idaho site sees ~160 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Atlantic White Cedar needs 140+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Atlantic White Cedar native to Idaho?
Atlantic White Cedar is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Idaho. It can still earn a place in a Idaho garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Atlantic White Cedar in Idaho?
Atlantic White Cedar prefers pH 3.5-5.5 and poorly (saturated >50% of year) drainage (Growable Ground Plant Database). Most Idaho soils run mildly acidic to neutral; many sites land near this band naturally, and a soil test plus targeted sulfur or organic amendment closes any gap.
Will Atlantic White Cedar actually grow on my specific land in Idaho?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores atlantic white cedar against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Idaho
State-level data is a sketch. Your Growable Ground report scores atlantic white cedar against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Idaho atlantic white cedar averages can't show:
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