Olmsted County, in Minnesota, sits in USDA hardiness zone 4b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Expect cabbage, cranberry, turkish rocket, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Olmsted County lies within the Driftless Area — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Olmsted County holds more than one microclimate.
Soils and elevations shift across Olmsted County, so your frost dates and drainage aren't the county average. 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 Olmsted County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Olmsted County — the short answer
Olmsted County, Minnesota: USDA zone 4b, about 185 days between hard freezes, across 418K acres.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 18
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 418K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 4b is Olmsted County's average, not your lot's — a low corner or a tree line moves it. Against Olmsted County's 185-day season, see what your own ground reads.
Heat in Olmsted County
Across a year, Olmsted County accumulates about 2,296 growing degree days above 50°F, about 31 more than the middle Minnesota county — ahead of 47 of Minnesota’s 87 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Olmsted County
Across Olmsted County, the ground is predominantly Mollisols, where Downs, Tama, and Rockton are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.2–6.7, slightly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
53%
Hydric soils
12%
Soil still varies lot by lot — soil types explained.
How the ground varies across Olmsted County
The USDA soil survey maps 64% of Olmsted County as well drained — but another 35% drains differently: 10% somewhat poorly drained, 10% moderately well drained.
Downs is the most extensive named soil at 18% of mapped acres, then Tama (6%) and Rockton (3%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Olmsted County
Each reading below is measured for Olmsted County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Olmsted County are well drained, in hydrologic group C — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Olmsted County runs about pH 6.2–6.7, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredOlmsted County runs about 185 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
MeasuredOlmsted County sits in USDA hardiness zone 4b.
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 Olmsted County is in
Olmsted County sits in the Driftless Area — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Olmsted County
We scored all 1,086 plants against Olmsted County's own USDA zone 4b and its own 185-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Minnesota profile.
Is it too late to plant in Olmsted County?
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 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 18 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
Documented around Olmsted County
- Japanese beetle2 documented records
- monarch butterfly1,949 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Olmsted County
USGS estimates 183,465 lb of Glyphosate on Olmsted County farmland in 2019, its largest by weight, ahead of Acetochlor (101,132 lb) and Metolachlor & Metolachlor-s (69,203 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Olmsted County — and how to grow with it.
We checked the federal record across Olmsted County — 1,085 documented sites across 7 of the 9 source types we track.
The most significant on record: 3 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Olmsted County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Olmsted County
Closest first, across Olmsted County. Listing isn't leaking, and distance isn't exposure.
- Kwik Trip #418Underground Storage Tanks · 2100 ft
- ReynoldsUnderground Storage Tanks · 0.6 mi
- Rochester Fire Dept Station #2Underground Storage Tanks · 0.6 mi
- Nw QuadrantUnderground Storage Tanks · 0.6 mi
- United Rental-fmr UniversalUnderground Storage Tanks · 0.6 mi
- Rochester Materials CoUnderground Storage Tanks · 0.6 mi
- Kwik Trip 364Underground Storage Tanks · 0.6 mi
- Silver Lake Fire StationUnderground Storage Tanks · 0.6 mi
- Graybar Electric(former Gamble Robinson)Underground Storage Tanks · 0.6 mi
- Formerly Goodman Auto RepairUnderground Storage Tanks · 0.6 mi
- WINKELS ELECTRIC SHOPBrownfields · 0.7 mi
- DALLAS TRUCK CENTERS INCBrownfields · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Olmsted County'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 Olmsted County.
Sources Checked
across Olmsted County
Severity Distribution
across Olmsted County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Olmsted County, two things run higher than the national average across Olmsted County — Brownfields (592 sites) and CAFO (10 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Olmsted County
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 Olmsted County average
Your land is one point inside Olmsted County
Everything above resolves to Olmsted County as a whole — one PHZM band and one county frost record, read across 418K 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 county 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 county average.
Your Lot vs the Olmsted County Average
Olmsted County Average
- ●USDA Zones 4b, averaged across Olmsted County
- ●One soil character for all of Olmsted County
- ●Frost dates read at Olmsted County's scale: Apr 16 to Oct 18
YOUR Parcel
- ✓Your exact zone, not Olmsted County's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Olmsted County
Pull a site-specific report for your exact address in Olmsted County, Minnesota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Olmsted County averages can't show:
We read public map data around Olmsted County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Olmsted County average
How we know this about Olmsted County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Olmsted County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Olmsted County
When does frost risk typically end in Olmsted County?
The last hard freeze (28°F) in Olmsted County typically lands around Apr 16, 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 7.
How long is the growing season in Olmsted County?
Measured between 28°F hard freezes, Olmsted County sees about 185 frost-free days — roughly Apr 16 through Oct 18, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 4, about 150 days.
Is the soil safe to grow vegetables in Olmsted County?
The federal record around Olmsted County is a meaningful one — 1,085 documented sites, mostly Brownfields entries (592), the nearest Underground Storage Tanks record about 0.4 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.
Everything above is measured at Olmsted County's scale — its 4b band and its 185-day season. Your yard writes its own version of Olmsted County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Minnesota's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Olmsted County’s own scale
9 of the readings below were taken at Olmsted County's own scale — its own ~185-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,085 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Olmsted County's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Olmsted County's own 28°F hard-freeze dates and its ~185-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Olmsted CountyUSDA NRCS SSURGO
- 1,085 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.4 miles outFederal environmental registers
- Olmsted County's boundary and the 418,246 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~185-day seasonGrowable Ground crop-matching engine
- Olmsted County sitting wholly inside the Driftless AreaUS EPA Level III Ecoregions
- Open occurrence records documented in Olmsted County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Olmsted County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Minnesota grower plans around — written at state scale, so they stay on the state guidefrom Minnesota
What this page can’t tell you
- How the season shifts across Olmsted County — the ~185 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Olmsted County's 418,246 acreswhy one lot differs from the next →
- Which of those 1,085 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Olmsted Countyread your own land →