Hamilton County, in Kansas, sits in USDA hardiness zone 6a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Well-matched crops include cabbage, hazelnut, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Hamilton County lies within the High Plains — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Hamilton County holds more than one microclimate.
Soils and elevations shift across Hamilton 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 Hamilton County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Hamilton County — the short answer
Hamilton County, Kansas: USDA zone 6a, about 185 days between hard freezes, across 638K acres.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 19
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 21
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 638K 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 6a is Hamilton County's average, not your lot's — a low corner or a tree line moves it. Against Hamilton County's 185-day season, see what your own ground reads.
Heat in Hamilton County
Across a year, Hamilton County accumulates about 3,498 growing degree days above 50°F, about 335 fewer than the middle Kansas county — ahead of 19 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 Hamilton County
Across Hamilton County, the ground is predominantly Mollisols, where Colby, Richfield, and Ulysses are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 7.2–7.9, slightly alkaline. Rainfall drains through hydrologic group B soils.
Soil order
Mollisols
Drainage
Well drained
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Hamilton County
The USDA soil survey maps 84% of Hamilton County as well drained — but another 16% drains differently: 11% excessively drained, 3% somewhat excessively drained.
Colby is the most extensive named soil at 34% of mapped acres, then Richfield (28%) and Ulysses (13%).
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 Hamilton County
Each reading below is measured for Hamilton 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 Hamilton County are well drained, in hydrologic group B — 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 Hamilton County runs about pH 7.2–7.9, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredHamilton 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
MeasuredHamilton County sits in USDA hardiness zone 6a.
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 Hamilton County is in
Hamilton County sits in the High Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Hamilton County
We scored all 1,086 plants against Hamilton County's own USDA zone 6a 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 Kansas profile.
Is it too late to plant in Hamilton County?
For most of the year, no — what changes is which crops still fit the days remaining. 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 21 — 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 gets applied to farmland in Hamilton County
USGS estimates 250,582 lb of Glyphosate on Hamilton County farmland in 2019, its largest by weight, ahead of Atrazine (137,499 lb) and 2,4-d (74,929 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 Hamilton County — and how to grow with it.
We checked the federal record across Hamilton County — 129 documented sites across 5 of the 9 source types we track.
The most significant on record: 1 Toxics Release Inventory facility. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Hamilton 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 Hamilton County
Closest first, across Hamilton County. Listing isn't leaking, and distance isn't exposure.
- PREMIUM CATTLE COMPANY LLCCAFO · 1.2 mi
- R & M IMPLEMENT INC.Underground Storage Tanks · 1.8 mi
- HAMILTON COUNTY WEED DEPTUnderground Storage Tanks · 2.2 mi
- HAMILTON COUNTY ROAD DEPTUnderground Storage Tanks · 2.2 mi
- RASH, GARYUnderground Storage Tanks · 2.2 mi
- 24S 40W 07CBB 01Nitrate · 2.2 mi
- HOLSTEIN SUPPLY INCBrownfields · 2.2 mi
- U PUMP IT CORNER STORE #201Underground Storage Tanks · 2.2 mi
- SYRACUSE FLYING SERVICE INCUnderground Storage Tanks · 2.3 mi
- EAGLE CONVENIENCE STOREUnderground Storage Tanks · 2.4 mi
- BEAR CREEK FEEDERSBrownfields · 2.4 mi
- USD #494Underground Storage Tanks · 2.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Hamilton 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 Hamilton County.
Total Sites
129
across Hamilton County
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
across Hamilton County
Severity Distribution
across Hamilton County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hamilton County, two things run higher than the national average across Hamilton County — CAFO (11 sites) and Nitrate (82 sites). That's not a problem with your land — it's information about 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 Hamilton 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 Hamilton County average
Your land is one point inside Hamilton County
Everything above resolves to Hamilton County as a whole — one PHZM band and one county frost record, read across 638K 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 Hamilton County Average
Hamilton County Average
- ●USDA Zones 6a, averaged across Hamilton County
- ●One soil character for all of Hamilton County
- ●Frost dates read at Hamilton County's scale: Apr 19 to Oct 21
YOUR Parcel
- ✓Your exact zone, not Hamilton County's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Hamilton County
Pull a site-specific report for your exact address in Hamilton County, Kansas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hamilton County averages can't show:
We read public map data around Hamilton County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hamilton County average
How we know this about Hamilton 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 Hamilton County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Hamilton County
When does frost risk typically end in Hamilton County?
The last hard freeze (28°F) in Hamilton County 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.
How long is the growing season in Hamilton County?
Measured between 28°F hard freezes, Hamilton County sees about 185 frost-free days — roughly Apr 19 through Oct 21, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 10 to Oct 7, about 150 days.
Is the soil safe to grow vegetables in Hamilton County?
The federal record around Hamilton County shows 129 documented sites, mostly Nitrate entries (82), the nearest CAFO record about 1.2 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 Hamilton County's scale — its 6a band and its 185-day season. Your yard writes its own version of Hamilton 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 Hamilton County’s own scale
8 of the readings below were taken at Hamilton County's own scale — its own ~185-day span between 28°F freezes, the 3 most extensive soil series mapped here and 129 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Hamilton County's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Hamilton 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 Hamilton CountyUSDA NRCS SSURGO
- 129 documented contamination sites inside the county boundary, distance-sorted from its center — the closest CAFO record about 1.2 miles outFederal environmental registers
- Hamilton County's boundary and the 637,768 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~185-day seasonGrowable Ground crop-matching engine
- Hamilton County sitting wholly inside the High PlainsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Hamilton 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 Hamilton 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 Hamilton County's 637,768 acreswhy one lot differs from the next →
- Which of those 129 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 Hamilton Countyread your own land →