Linn County, in Kansas, sits in USDA hardiness zone 6b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, hazelnut, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Linn County lies within the Southeast Kansas / Cherokee Lowlands (Ozark Border) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Linn County holds more than one microclimate.
Soils and elevations shift across Linn 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 Linn County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Linn County — the short answer
Linn County, Kansas: USDA zone 6b, about 220 days between hard freezes, across 380K acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 31
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 6
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~220
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 380K 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 6b is Linn County's average, not your lot's — a low corner or a tree line moves it. Against Linn County's 220-day season, see what your own ground reads.
Heat in Linn County
Across a year, Linn County accumulates about 3,882 growing degree days above 50°F, about 49 more than the middle Kansas county — ahead of 60 of Kansas’s 105 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 Linn County
Across Linn County, the ground is predominantly Mollisols, where Kenoma, Wagstaff, and Summit are the most extensive named soil series. The soil is generally moderately well drained with a silty clay loam surface. Topsoil pH runs about 6.1–6.5, slightly acidic. Rainfall drains through hydrologic group D soils.
Soil order
Mollisols
Drainage
Moderately well drained
Prime farmland
65%
Hydric soils
6%
Soil still varies lot by lot — soil types explained.
How the ground varies across Linn County
The USDA soil survey maps 49% of Linn County as moderately well drained — but another 49% drains differently: 24% well drained, 19% somewhat poorly drained.
Kenoma is the most extensive named soil at 14% of mapped acres, then Wagstaff (13%) and Summit (10%).
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 Linn County
Each reading below is measured for Linn 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 Linn County are moderately well drained, in hydrologic group D — roughly the middle of the drainage range.
This is close to the middle most vegetables prefer: it holds enough water to carry a crop between rains without staying waterlogged. The catch is that a wet spring or a low corner can still tip it soggy.
Plant on the site as-is for most crops, but keep the lowest, slowest-draining beds for moisture-tolerant plantings.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Linn County runs about pH 6.1–6.5, 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
MeasuredLinn County runs about 220 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredLinn County sits in USDA hardiness zone 6b.
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 Linn County is in
Linn County sits in the Central Irregular Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Linn County
We scored all 1,086 plants against Linn County's own USDA zone 6b and its own 220-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 Kansas profile.
Is it too late to plant in Linn County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 31 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 6 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
Documented around Linn County
- monarch butterfly13 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Linn County
USGS estimates 125,329 lb of Glyphosate on Linn County farmland in 2019, its largest by weight, ahead of Acephate (88,135 lb) and Metolachlor & Metolachlor-s (67,045 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 Linn County — and how to grow with it.
We checked the federal record across Linn County — 126 documented sites across 5 of the 9 source types we track.
The most significant on record: 4 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Linn County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Linn County
Closest first, across Linn County. Listing isn't leaking, and distance isn't exposure.
- 21S 23E 26DAA 01Nitrate · 1.7 mi
- 21S 24E 08CDA 01Nitrate · 2.8 mi
- 20S 23E 36CB 01Nitrate · 3.4 mi
- 21S 24E 29DAC 01Nitrate · 3.5 mi
- 22S 23E 12AAD 01Nitrate · 4.5 mi
- 21S 23E 06A 01Nitrate · 4.9 mi
- 21S 23E 06CA 01Nitrate · 5.0 mi
- 21S 23E 31DCD 01Nitrate · 5.1 mi
- LINN CNTY HWY DEPTBrownfields · 5.3 mi
- CASEY'S GENERAL STORE - #1306Underground Storage Tanks · 5.3 mi
- A1 TIRE & AUTOBrownfields · 5.4 mi
- MOTO POWER GAS & OIL CO.Underground Storage Tanks · 5.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Linn 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 Linn County.
Total Sites
126
across Linn County
Risk Level
Moderate
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
across Linn County
Severity Distribution
across Linn County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Linn County, Nitrate runs higher than the national average — 74 sites across Linn County. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Linn 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 Linn County average
Your land is one point inside Linn County
Everything above resolves to Linn County as a whole — one PHZM band and one county frost record, read across 380K 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 Linn County Average
Linn County Average
- ●USDA Zones 6b, averaged across Linn County
- ●One soil character for all of Linn County
- ●Frost dates read at Linn County's scale: Mar 31 to Nov 6
YOUR Parcel
- ✓Your exact zone, not Linn County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Linn County
Pull a site-specific report for your exact address in Linn County, Kansas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Linn County averages can't show:
We read public map data around Linn County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Linn County average
How we know this about Linn 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 Linn County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Linn County
When does frost risk typically end in Linn County?
The last hard freeze (28°F) in Linn County typically lands around Mar 31, 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 Apr 21.
How long is the growing season in Linn County?
Measured between 28°F hard freezes, Linn County sees about 220 frost-free days — roughly Mar 31 through Nov 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 21 to Oct 23, about 185 days.
Is the soil safe to grow vegetables in Linn County?
The federal record around Linn County shows 126 documented sites, mostly Nitrate entries (74), the nearest Nitrate record about 1.7 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
Everything above is measured at Linn County's scale — its 6b band and its 220-day season. Your yard writes its own version of Linn 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 Kansas's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Linn County’s own scale
9 of the readings below were taken at Linn County's own scale — its own ~220-day span between 28°F freezes, the 3 most extensive soil series mapped here and 126 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Linn County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Linn County's own 28°F hard-freeze dates and its ~220-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Linn CountyUSDA NRCS SSURGO
- 126 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 1.7 miles outFederal environmental registers
- Linn County's boundary and the 380,211 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~220-day seasonGrowable Ground crop-matching engine
- Linn County sitting wholly inside the Central Irregular PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Linn County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Linn County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Kansas grower plans around — written at state scale, so they stay on the state guidefrom Kansas
What this page can’t tell you
- How the season shifts across Linn County — the ~220 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 Linn County's 380,211 acreswhy one lot differs from the next →
- Which of those 126 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 Linn Countyread your own land →