Flensburg, Minnesota, sits in USDA hardiness zone 4a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — cabbage, cranberry, turkish rocket, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Flensburg, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Flensburg lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Flensburg — soil, climate, flood, and parcel records. How we handle your address.
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Flensburg — the short answer
Flensburg, Minnesota: USDA zone 4a, about 165 days between hard freezes, across 4K acres of city.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 28
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~165
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 4K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 4a is Flensburg's average, not your lot's — a low corner or a tree line moves it. Against Flensburg's 165-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Flensburg
Each reading below is measured for Flensburg itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFlensburg runs about 165 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredFlensburg sits in USDA hardiness zone 4a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Flensburg is in
Flensburg sits in the North Central Hardwood Forests — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Flensburg's own centroid rather than borrowed from Morrison County.
What Grows in Flensburg
Every plant below cleared Flensburg's own zone 4a and its 165-day season. Each card opens that plant's Minnesota profile. How we score.
Is it too late to plant in Flensburg?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 31; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 28 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 10 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Flensburg
Closest first, within ~10 miles of Flensburg. Listing isn't leaking, and distance isn't exposure.
- Jerrys TexacoUnderground Storage Tanks · 2400 ft
- THIRTEEN ACRES INC - SEC 27CAFO · 1.8 mi
- 113825Nitrate · 2.0 mi
- 454542Nitrate · 2.7 mi
- Polish PalaceUnderground Storage Tanks · 3.3 mi
- Sobieski Coop Creamery AssnUnderground Storage Tanks · 3.3 mi
- Pillsbury Burnhamville TownshipUnderground Storage Tanks · 3.9 mi
- Pillsbury StoreUnderground Storage Tanks · 3.9 mi
- WILWERDING POULTRY FARMCAFO · 4.0 mi
- SCHERPING FARMS OF LITTLE FALCAFO · 4.0 mi
- WISHBONE ACRES LLCCAFO · 4.3 mi
- 12 Mile TavernUnderground Storage Tanks · 4.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Flensburg's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Flensburg.
Total Sites
223
within ~10 miles of Flensburg
Risk Level
Elevated
Highest-severity
9 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Flensburg
Severity Distribution
within ~10 miles of Flensburg
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Flensburg, CAFO runs higher than the national average — 13 sites within ~10 miles of Flensburg. That's not a problem with your land — it's information about it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Flensburg
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Flensburg average
Your land is one point inside Flensburg
Everything above resolves to Flensburg as a whole — one PHZM band and one 28°F frost record, read across 4K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at city scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Flensburg Average
Flensburg Average
- ●USDA Zones 4a, averaged across Flensburg
- ●One soil character for all of Flensburg
- ●Frost dates read at Flensburg's scale: Apr 28 to Oct 10
YOUR Parcel
- ✓Your exact zone, not Flensburg's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Flensburg
Pull a site-specific report for your exact address in Flensburg, Minnesota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Flensburg averages can't show:
We read public map data around Flensburg — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Flensburg average
How we know this about Flensburg
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Flensburg’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Flensburg
When does frost risk typically end in Flensburg?
The last hard freeze (28°F) in Flensburg typically lands around Apr 28, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 19.
When is the first frost in Flensburg?
The first hard freeze (28°F) in Flensburg typically arrives around Oct 10, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 26, so the watching starts about Sep 10 — about 165 days after the spring freeze cleared.
How long is the growing season in Flensburg?
Measured between 28°F hard freezes, Flensburg sees about 165 frost-free days — roughly Apr 28 through Oct 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 19 to Sep 26, about 130 days.
Is the soil safe to grow vegetables in Flensburg?
The federal record around Flensburg is a meaningful one — 223 documented sites, mostly Brownfields entries (84), the nearest Underground Storage Tanks record about 0.5 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Flensburg?
From about Sep 10 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 10 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 10. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Flensburg's scale — its 4a band and its 165-day season. Your yard writes its own version of Flensburg's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Flensburg’s own scale
6 of the readings below were taken at Flensburg's own scale — its own ~165-day season between 28°F freezes, the 4,467 acres it covers and 223 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Flensburg's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Flensburg's own 28°F hard-freeze dates, about Apr 28 and Oct 10 and the ~165-day span between themNOAA 1991–2020 Climate Normals
- 223 documented contamination sites on the federal record near Flensburg, the closest Underground Storage Tanks record about 0.5 miles out from the town centreFederal environmental registers
- Flensburg's boundary and the 4,467 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~165-day seasonGrowable Ground crop-matching engine
- The ecoregion at Flensburg's own centroid, the North Central Hardwood ForestsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Flensburg's 4,467 acres read through its county's SSURGO summaryfrom Morrison County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Morrison County
- The growing challenges every Minnesota grower plans around — written at state scale, so they stay on the state guidefrom Minnesota
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Morrison County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Flensburg's 4,467 acreswhy one lot differs from the next →
- Which side of Flensburg you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,467 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.5 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Flensburg-wide figureread your own land →
More in Minnesota
Wider growing context
What grows across MinnesotaFlensburg sits outside our named growing regions, so Minnesota as a whole is its closest context here.
Nearby growing guides