Round Lake, Minnesota, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with cabbage, cranberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Round Lake, 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 Round Lake 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 Round Lake — soil, climate, flood, and parcel records. How we handle your address.
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Round Lake — the short answer
Round Lake, Minnesota: USDA zone 5a, about 179 days between hard freezes, across 464 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 19
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 15
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~179
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 464 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 5a is Round Lake's average, not your lot's — a low corner or a tree line moves it. Against Round Lake's 179-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Round Lake
Each reading below is measured for Round Lake itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRound Lake runs about 179 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
MeasuredRound Lake sits in USDA hardiness zone 5a.
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 Round Lake is in
Round Lake sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Round Lake's own centroid rather than borrowed from Nobles County.
What Grows in Round Lake
Every plant below cleared Round Lake's own zone 5a and its 179-day season. Each card opens that plant's Minnesota profile. How we score.
Is it too late to plant in Round Lake?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 22; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 19 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 15 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Round Lake
Closest first, within ~10 miles of Round Lake. Listing isn't leaking, and distance isn't exposure.
- Ag-chem Equipment Co IncUnderground Storage Tanks · 1300 ft
- Nobles County Coop Oil C StoreUnderground Storage Tanks · 1300 ft
- 101N39W24BBD 03 Round LakeNitrate · 1400 ft
- FARLEY'S & SATHERS CANDY CO INC ROUND LKBrownfields · 1500 ft
- Round Lake Pit StopUnderground Storage Tanks · 1900 ft
- WILSON SITECAFO · 1.7 mi
- FRANK RILEY FARMCAFO · 2.6 mi
- 101N39W33DAA 01 A FeltmanNitrate · 3.0 mi
- Sather Trucking/nabisco IncUnderground Storage Tanks · 3.1 mi
- 100N39W17DCCB 25108 1978IGS CRET Proj D-13Nitrate · 4.3 mi
- 100N39W17DCCB 25108 1978IGS CRET Proj D-13 (Deep)Nitrate · 4.3 mi
- 494012Nitrate · 5.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Round Lake'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 Round Lake.
Total Sites
212
within ~10 miles of Round Lake
Risk Level
Elevated
Highest-severity
8 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Round Lake
Severity Distribution
within ~10 miles of Round Lake
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Round Lake, two things run higher than the national average within ~10 miles of Round Lake — CAFO (7 sites) and Nitrate (56 sites). 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.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Round Lake
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 Round Lake average
Your land is one point inside Round Lake
Everything above resolves to Round Lake as a whole — one PHZM band and one 28°F frost record, read across 464 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 Round Lake Average
Round Lake Average
- ●USDA Zones 5a, averaged across Round Lake
- ●One soil character for all of Round Lake
- ●Frost dates read at Round Lake's scale: Apr 19 to Oct 15
YOUR Parcel
- ✓Your exact zone, not Round Lake's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Round Lake
Pull a site-specific report for your exact address in Round Lake, Minnesota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Round Lake averages can't show:
We read public map data around Round Lake — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Round Lake average
How we know this about Round Lake
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 Round Lake’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 Round Lake
When does frost risk typically end in Round Lake?
The last hard freeze (28°F) in Round Lake typically lands around Apr 19, 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 10.
When is the first frost in Round Lake?
The first hard freeze (28°F) in Round Lake typically arrives around Oct 15, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 1, so the watching starts about Sep 15 — about 179 days after the spring freeze cleared.
How long is the growing season in Round Lake?
Measured between 28°F hard freezes, Round Lake sees about 179 frost-free days — roughly Apr 19 through Oct 15, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 10 to Oct 1, about 144 days.
Is the soil safe to grow vegetables in Round Lake?
The federal record around Round Lake is a meaningful one — 212 documented sites, mostly Brownfields entries (76), the nearest Underground Storage Tanks record about 0.2 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 Round Lake?
From about Sep 15 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 15 (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 15. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Round Lake's scale — its 5a band and its 179-day season. Your yard writes its own version of Round Lake'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 Round Lake’s own scale
6 of the readings below were taken at Round Lake's own scale — its own ~179-day season between 28°F freezes, the 464 acres it covers and 212 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Round Lake's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Round Lake's own 28°F hard-freeze dates, about Apr 19 and Oct 15 and the ~179-day span between themNOAA 1991–2020 Climate Normals
- 212 documented contamination sites on the federal record near Round Lake, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Round Lake's boundary and the 464 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~179-day seasonGrowable Ground crop-matching engine
- The ecoregion at Round Lake's own centroid, the Western Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Round Lake's 464 acres read through its county's SSURGO summaryfrom Nobles County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Nobles 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 Nobles County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Round Lake's 464 acreswhy one lot differs from the next →
- Which side of Round Lake you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 464 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 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 Round Lake-wide figureread your own land →
More in Minnesota
Wider growing context
What grows across MinnesotaRound Lake sits outside our named growing regions, so Minnesota as a whole is its closest context here.
Nearby growing guides