Yes — Strong Match
onion is grown in zones 2-11, which covers every zone Minnesota contains (3a-5a). Whether the season is long enough is the question that remains.
Onion in Minnesota — the short answer
Onion in Minnesota: grown in zones 2–11, full sun.
- Plant zones
- 2-11
- Not verified — NC State Extension Gardener Plant Toolbox lists zones 5a–10b
- Minnesota zones
- 3a-5a
- USDA PHZM 2023
- Frost window
- Apr 19 - Apr 30 – Oct 10 - Oct 17
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 137 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 110 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Minnesota spans zones 3a-5a, 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 onion against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Minnesota is not one climate
A single Minnesota answer averages 87 counties whose growing seasons are 62 days apart — from 137 frost-free days in Lake County to 199 in Ramsey County. Which end of that your land sits nearer changes what onion can finish before the first hard freeze.
The middle half of 87 counties runs 162–181 days, with a median of 174 days — a 62-day span end to end.
Measured across 87 Minnesota counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Minnesota Fits Best
Even within Minnesota's zones 3a-5a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for onion (USDA PHZM 2023):
Zone Comparison
Onion Needs
- USDA Zones: 2-11
- Sun: Full Sun
- Mature size: 1.5 ft tallWe haven't confirmed this against a published source yet.
- Picking window: ~7 days of harvestWe haven't confirmed this against a published source yet.
- Drought tolerance: MediumWe haven't confirmed this against a published source yet.
Minnesota Has
- USDA Zones: 3a-5a
- Last Hard Freeze (28°F): Apr 19 - Apr 30
- First Hard Freeze (28°F): Oct 10 - Oct 17
- Annual Rainfall: 19-34 inches
- Common Soils: Prairie loam, Clay, Sandy outwash
Plant Zone Range (zones 2-11)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Onion in Minnesota
The frost window
Across Minnesota, the last spring hard freeze (28°F) clears between Apr 19 and Apr 30, and the first fall hard freeze lands between Oct 10 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 163-day window you can count on — up to 181 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.
When to start the seed
Those dates are when onion goes out, not when it starts. It is sown under cover about 9 weeks ahead, so counting back from Minnesota's late-side last freeze of Apr 30 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Grown as an annual here
Onion is a true perennial in its home range — it overwinters from USDA zone 5 and warmer (NC State Extension Gardener Plant Toolbox) — but Minnesota runs as cold as zone 3, so it is killed back each winter and replanted each spring. Treat it on the season schedule above, not as a permanent planting: there is no fall establishment window for it here.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
Onion is grown in zones 2–11, which covers every zone Minnesota contains (3a-5a). It overwinters in the ground only in zone 5 and warmer (NC State Extension Gardener Plant Toolbox). Minnesota's typical season runs ~174 frost-free days against the ~85 onion needs.
Growing degree days
Onion needs ~1700 GDD (base 50°F) to ripen. We haven't confirmed this against a published source yet. The state median runs ~1920 GDD (from PRISM 1991-2020 climate normals), so Minnesota sits right at the threshold — pay attention to siting and microclimate.
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
Onion tolerates a wide pH range (pH 4.3-8.3) — 4 units, acid ground through alkaline — so soil acidity is rarely what limits it in Minnesota. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 6 and 7 — worth knowing before you decide whether a Minnesota soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Minnesota site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Minnesota soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant onion for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before onion goes in. What follows is Minnesota’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Minnesota — and how to grow with it.
We checked the federal record across Minnesota — 18,030 documented sites across 7 of the 8 source types we track.
The most significant on record: 172 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Minnesota carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds of imported, lab-tested soil grow well almost anywhere in the meantime.
Sources Checked
across Minnesota
Severity Distribution
across Minnesota
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Minnesota, CAFO runs higher than the national average — 1,010 sites across Minnesota. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Sources: EPA, USGS — 950K documented sites tracked nationwide across 8 federal source types.
What Else to Consider for Onion in Minnesota
The zone range tells you where onion is grown — but Minnesota growers also need to think about:
Extreme cold (zone 3a: -40F) limits many species
Short growing season (100-140 frost-free days)
Heavy clay soils in the Red River Valley
What to actually do about these — and the constraints that apply to every Minnesota grower, not just onion — is covered on the Minnesota growing guide.
Where in Minnesota Onion Is Zone-Hardy
Onion is rated for USDA zones 2–11. Every one of Minnesota’s 87 counties sits inside that band — from Beltrami County at zone 3b to Watonwan County at zone 5a — so winter cold is not what decides this plant anywhere in the state. What is left to vary is your own parcel: slope, shelter and cold-air drainage routinely move a site half a zone either way from the county figure.
Across those 87 counties Minnesota’s winter-low ladder runs from zone 3b in Beltrami County to zone 5a in Watonwan County — 1.5 USDA zones of spread, which is 15°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Lake County holds its last hard freeze (28°F) until about May 14, while Ramsey County is clear by Apr 10 — 34 days apart. Set onion out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Onion’s zone 2–11 band: Not verified — NC State Extension Gardener Plant Toolbox lists zones 5a–10b. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Onion draws honeybees, native bees, and butterflies (moderate value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, onion can only work that bloom inside Minnesota's frost window — roughly 174 days, opening after the last 28°F freeze (Apr 19 - Apr 30) and closing at the first (Oct 10 - Oct 17), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.
Minnesota Cooperative Extension
For Minnesota-specific cultivar recommendations, planting calendars, and pest pressure for onion, the canonical source is University of Minnesota Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Onion native to Minnesota?
No — the USDA PLANTS Database lists Onion as introduced rather than native in the Lower 48, so it is not part of Minnesota's native flora. It grows here as a garden plant; pairing it with a few Minnesota natives keeps local pollinators fed too.
Looking for plants that belong here? The Minnesota growing guide lists plants that USDA PLANTS records growing in Minnesota and that Kew and NatureServe Explorer both list in its native range, leaving out any that NatureServe flags as exotic there or that our audit holds.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Onion in Minnesota
When can I plant Onion in Minnesota?
Minnesota's last spring hard freeze (28°F) clears between Apr 19 and Apr 30, and the first fall hard freeze lands between Oct 10 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Onion overwinters only from USDA zone 5 and warmer, and Minnesota runs as cold as zone 3, so it is grown as an annual here — plant it after the last hard freeze, two to three weeks later for tender stock, and expect to replant next spring rather than establishing it for the long term.
What hardiness zone is Onion grown in across Minnesota?
Minnesota spans USDA hardiness zones 3a-5a (USDA ARS PHZM 2023). Onion 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 Minnesota site have?
A typical Minnesota site sees ~174 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Onion needs 85+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Onion native to Minnesota?
No — the USDA PLANTS Database lists Onion as introduced rather than native in the Lower 48, so it is not part of Minnesota's native flora. It grows here as a garden plant; pairing it with a few Minnesota natives keeps local pollinators fed too.
How should I amend the soil for Onion in Minnesota?
Onion tolerates pH 4.3-8.3 and well (dry spells) drainage (FAO ECOCROP). That is a 4-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Minnesota site — amend for drainage and organic matter first.
Will Onion actually grow on my specific land in Minnesota?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores onion against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Minnesota
State-level data is a sketch. Your Growable Ground report scores onion against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Minnesota onion averages can't show:
We read public map data around Minnesota — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Minnesota onion average
Explore More
Growing guides for onion
Explore Minnesota county by county
Minnesota carries 87 counties with their own USDA zone — a sample of the growing pages for onion there:
Where else onion grows
Onion's zone band crosses state lines — these are the states closest to Minnesota in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Minnesota
Minnesota has a growing page for 752 plants — a rotating sample of the rest of the shelf.
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