Generally — Most Areas
acorn squash (zones 2-11) partially overlaps with Idaho (3b-7a). It can grow in zones 3-7 within the state.
Your yard isn't the whole zone.
Acorn Squash is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is, and slope, trees, and low spots move the last-frost date across a single yard. Enter your address and we'll score acorn squash against your parcel's actual frost dates, sun, and soil.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Zone Comparison
Acorn Squash Needs
- USDA Zones: 2-11
- Soil pH: 4.5 - 8.3
- Sun: Full Sun
- Drainage: well (dry spells)
- Frost-Free Days: 40+
Idaho Has
- USDA Zones: 3b-7a
- Last Frost: Apr 15 - Jun 15
- First Frost: Sep 1 - Oct 15
- Annual Rainfall: 8-35 inches
- Common Soils: Volcanic ash, Silt loam, Sandy loam
Plant Zone Range (zones 2-11)
Preferred Soil pH
Plant data: USDA PLANTS Database / plant_species_v5.csv. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Acorn Squash in Idaho
The frost window
Across Idaho, the last spring frost clears between Apr 15 and Jun 15, and the first fall frost lands between Sep 1 and Oct 15 (NOAA Climate Normals 1991-2020). Counting from the latest last frost to the earliest first frost, that's a 78-day window you can count on — up to 183 days on a mild site in a kind year.
Frost tenderness
Acorn Squash is frost-tender — its listed minimum temperature is 42.8°F (USDA PLANTS Database) — so set plants out after the last frost has cleared your local site, not the state's earliest date.
Days to maturity vs. the window
At 55 days to maturity (USDA PLANTS Database), one crop fits Idaho's 78-day dependable window with 23 days of margin — plant at the front of the window to keep that cushion.
Timing tuned to sub-state frost dates — Valley County, not the statewide average.
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
Zone compatibility says you can survive winter here. Whether the growing season is long enough — and warm enough — is a different question.
Frost-free days
Acorn Squash wants 40+ frost-free days; a typical Idaho site sees ~150 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Growing degree days
Acorn Squash needs ~1100 GDD (base 50°F) to ripen. The state median runs ~2700 GDD (USDA NRCS county aggregates), so Idaho's typical season clears that easily.
Climate aggregates derive from USDA NRCS county-level hardiness data + Cornell CALS Extension GDD-by-region tables + MSU Extension chill-hours-by-zone (1991-2020 NOAA Climate Normals baseline).
Soil + Drainage Fit
Acorn Squash likes near-neutral soil (pH 4.5-8.3). That's the common-ground band across Idaho's volcanic ash and silt loam — a soil test confirms it for your site. Drainage matters: this plant wants well (dry spells). If your Idaho site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Idaho's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel — that map unit, not the state average, decides how acorn squash performs.
Check your parcel → Source: USDA NRCS SSURGO.
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.
Acorn Squash in Idaho — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 2-11 (USDA PLANTS Database)
- State Zones: 3b-7a (USDA ARS PHZM 2023)
- Growing Season: Apr 15 - Jun 15 to Sep 1 - Oct 15 (NOAA Climate Normals)
- Days to Maturity: 55 days
What Else to Consider
Zone compatibility tells you about winter cold survival — but Idaho growers also need to think about:
Short growing season at higher elevations
At elevation, fast varieties plus a cold frame or low tunnel reliably buy back the weeks the calendar withholds.
Arid conditions require irrigation in most of the state
Drip irrigation and deep mulch are the arid-country baseline — set the water system before the plants.
Cold winter snaps can reach -30F in mountain valleys
Plant perennials for your real zone, not an optimistic one — a -30°F night finds every zone-pushed plant.
Growing acorn squash here specifically
Acorn Squash wants pH 4.5–8.3 and rates to USDA zones 2–11, but Idaho's soils are dominantly silt loam — the fit is decided by your parcel's own map unit, not the state average.
Match acorn squash to your parcel's SSURGO map unit — test pH and texture, and amend toward its 4.5–8.3 range. How to handle it →
Timing shifts within Idaho
Idaho isn't one climate. In Valley County, the last hard freeze (28°F) holds until about Jun 1 — roughly 42 days later than the recorded state median — so plant acorn squash to your county's window, not the statewide date.
County last-freeze dates: NOAA/PRISM Climate Normals 1991-2020, 28°F threshold (earlier than the folk 32°F "last frost"). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Acorn Squash draws pollinators (moderate value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops.
Idaho Cooperative Extension
For Idaho-specific cultivar recommendations, planting calendars, and pest pressure for acorn squash, the canonical source is University of Idaho Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Acorn Squash native to Idaho?
No — the USDA PLANTS Database lists Acorn Squash as introduced rather than native in the Lower 48, so it is not part of Idaho's native flora. It grows here as a garden plant; pairing it with a few Idaho natives keeps local pollinators fed too.
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 Acorn Squash in Idaho
When can I plant Acorn Squash in Idaho?
Idaho's last spring frost clears between Apr 15 and Jun 15, and the first fall frost lands between Sep 1 and Oct 15 (NOAA Climate Normals 1991-2020). Acorn Squash is frost-tender — its listed minimum temperature is 42.8°F (USDA PLANTS Database) — so wait until the last frost has cleared your specific site before planting out.
Can Acorn Squash mature before first frost in Idaho?
Yes — Acorn Squash matures in 55 days (USDA PLANTS Database), and Idaho's dependable frost-free window runs 78 days (NOAA Climate Normals 1991-2020), leaving 23 days of margin. Plant just after last frost and it ripens ahead of the first fall frost.
What hardiness zone is Acorn Squash grown in across Idaho?
Idaho spans USDA hardiness zones 3b-7a (USDA ARS PHZM 2023). Acorn Squash carries a range of zones 2-11, 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 ~150 frost-free days per year (derived from NOAA Climate Normals 1991-2020). Acorn Squash needs 40+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Valley, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Acorn Squash native to Idaho?
No — the USDA PLANTS Database lists Acorn Squash as introduced rather than native in the Lower 48, so it is not part of Idaho's native flora. It grows here as a garden plant; pairing it with a few Idaho natives keeps local pollinators fed too.
How should I amend the soil for Acorn Squash in Idaho?
Acorn Squash prefers pH 4.5-8.3 and well (dry spells) drainage (USDA PLANTS Database). That sits in the common-ground band across Idaho soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Acorn Squash actually grow on my specific land in Idaho?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores acorn squash 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 acorn squash against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →