Cimarron County, in Oklahoma, sits in USDA hardiness zone 6b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with cabbage, hazelnut, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Cimarron County lies within the Oklahoma Panhandle ("No Man's Land") and 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
Cimarron County holds more than one microclimate.
Soils and elevations shift across Cimarron 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 Cimarron County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Cimarron County — the short answer
Cimarron County, Oklahoma: USDA zone 6b, about 197 days between hard freezes, across 1.2M acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 13
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 27
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~197
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.2M 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 Cimarron County's average, not your lot's — a low corner or a tree line moves it. Against Cimarron County's 197-day season, see what your own ground reads.
Heat in Cimarron County
Across a year, Cimarron County accumulates about 3,532 growing degree days above 50°F, about 1,188 fewer than the middle Oklahoma county — no other Oklahoma county banks fewer. 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 Cimarron County
Across Cimarron County, the ground is predominantly Mollisols, where Dalhart, Sherm, and Conlen are the most extensive named soil series. The soil is generally well drained with a 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
Prime farmland
23%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Cimarron County
The USDA soil survey maps 92% of Cimarron County as well drained — but another 7% drains differently: 7% somewhat excessively drained.
Dalhart is the most extensive named soil at 27% of mapped acres, then Sherm (17%) and Conlen (14%).
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 Cimarron County
Each reading below is measured for Cimarron 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 Cimarron 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 Cimarron 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
MeasuredCimarron County runs about 197 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
MeasuredCimarron 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 Cimarron County is in
Cimarron County spans 2 EPA Level III ecoregions — High Plains (82%) and Southwestern Tablelands (18%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Cimarron County
We scored all 1,086 plants against Cimarron County's own USDA zone 6b and its own 197-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 Oklahoma profile.
Is it too late to plant in Cimarron County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 27 — 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 gets applied to farmland in Cimarron County
USGS estimates 110,656 lb of Atrazine on Cimarron County farmland in 2019, its largest by weight, ahead of Glyphosate (102,407 lb) and 2,4-d (62,804 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 Cimarron County — and how to grow with it.
We checked the federal record across Cimarron County — 157 documented sites across 4 of the 9 source types we track.
The most significant on record: 7 mining sites (prospects, none worked). Historic and active mines that may leach heavy metals like arsenic, lead, and cadmium.
The federal record across Cimarron 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 Cimarron County
Closest first, across Cimarron County. Listing isn't leaking, and distance isn't exposure.
- 03N-05E-10 DBB 1Nitrate · 0.8 mi
- Farmer ConstructionUnderground Storage Tanks · 0.9 mi
- Boise City Oil CompanyUnderground Storage Tanks · 1.0 mi
- Boise City Body Shop, Inc.Underground Storage Tanks · 1.1 mi
- Cimarron Implement CompanyUnderground Storage Tanks · 1.1 mi
- Love's Travel Stop #302Underground Storage Tanks · 1.3 mi
- Ftsw-Boise City Central OfficeUnderground Storage Tanks · 1.3 mi
- T03N-R05E-8 CDA 1 COS-1056Nitrate · 1.3 mi
- Boise City Public Work AuthoritUnderground Storage Tanks · 1.4 mi
- Public Works AuthorityUnderground Storage Tanks · 1.4 mi
- Toot 'N Totum #110Underground Storage Tanks · 1.4 mi
- Boise City AirportUnderground Storage Tanks · 1.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Cimarron 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 Cimarron County.
Total Sites
157
across Cimarron County
Risk Level
Moderate
Highest-severity
7 mining sites (prospects, none worked)
Sources Checked
across Cimarron County
Severity Distribution
across Cimarron County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Cimarron County, two things run higher than the national average across Cimarron County — CAFO (7 sites) and Nitrate (108 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Cimarron 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 Cimarron County average
Your land is one point inside Cimarron County
Everything above resolves to Cimarron County as a whole — one PHZM band and one county frost record, read across 1.2M 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 Cimarron County Average
Cimarron County Average
- ●USDA Zones 6b, averaged across Cimarron County
- ●One soil character for all of Cimarron County
- ●Frost dates read at Cimarron County's scale: Apr 13 to Oct 27
YOUR Parcel
- ✓Your exact zone, not Cimarron County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Cimarron County
Pull a site-specific report for your exact address in Cimarron County, Oklahoma — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Cimarron County averages can't show:
We read public map data around Cimarron County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Cimarron County average
How we know this about Cimarron 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 Cimarron County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Cimarron County
When does frost risk typically end in Cimarron County?
The last hard freeze (28°F) in Cimarron County typically lands around Apr 13, 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 4.
How long is the growing season in Cimarron County?
Measured between 28°F hard freezes, Cimarron County sees about 197 frost-free days — roughly Apr 13 through Oct 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 4 to Oct 13, about 162 days.
Is the soil safe to grow vegetables in Cimarron County?
The federal record around Cimarron County shows 157 documented sites, mostly Nitrate entries (108), the nearest Nitrate record about 0.8 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 Cimarron County's scale — its 6b band and its 197-day season. Your yard writes its own version of Cimarron 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 Oklahoma's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Cimarron County’s own scale
8 of the readings below were taken at Cimarron County's own scale — its own ~197-day span between 28°F freezes, the 3 most extensive soil series mapped here and 157 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Cimarron County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Cimarron County's own 28°F hard-freeze dates and its ~197-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Cimarron CountyUSDA NRCS SSURGO
- 157 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 0.8 miles outFederal environmental registers
- Cimarron County's boundary and the 1,174,276 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~197-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Cimarron County spans, High Plains the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Cimarron County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Oklahoma grower plans around — written at state scale, so they stay on the state guidefrom Oklahoma
What this page can’t tell you
- How the season shifts across Cimarron County — the ~197 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 Cimarron County's 1,174,276 acreswhy one lot differs from the next →
- Which of those 157 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 Cimarron Countyread your own land →