Park County, in Wyoming, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Reliable performers under these conditions include okra, cranberry, lavender, and pumpkin; what your own ground favors still comes down to its soil, sun, and drainage.
Park County lies within the Bighorn Basin — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Park County holds more than one microclimate.
Soils and elevations shift across Park 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 Park County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Park County — the short answer
Park County, Wyoming: USDA zone 5a, about 117 days between hard freezes, across 4.4M acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 27
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Sep 21
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~117
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 4.4M 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 5a is Park County's average, not your lot's — a low corner or a tree line moves it. Against Park County's 117-day season, see what your own ground reads.
One county, several growing seasons
Park County's hard-freeze record runs about 117 days between freezes — but that is the county-wide average, and several towns inside it carry a markedly different season in their own 30-year record: Garland at about 159 days (against the county's ~117).
Those are measured records, not estimates. If you garden in one of these pockets, plant against your own town's season rather than the county's ~117-day average.
NOAA Regional Climate Centers ACIS (1991–2020), 30-year daily minimum record. Only held-out towns carrying their own record are named — a town with no record of its own is absent rather than estimated, and a county with nothing qualifying shows no spread at all.
Heat in Park County
Across a year, Park County accumulates about 701 growing degree days above 50°F, about 1,173 fewer than the middle Wyoming county — ahead of 3 of Wyoming’s 23 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 Park County
Across Park County, the ground is predominantly Aridisols, where Hiland, Fughes-like, and Maysdorf are the most extensive named soil series. The soil is generally well drained with a sandy loam surface. Topsoil pH runs about 7.2–7.8, slightly alkaline. Rainfall drains through hydrologic group C soils.
Soil order
Aridisols
Drainage
Well drained
Hydric soils
2%
Soil still varies lot by lot — soil types explained.
How the ground varies across Park County
The USDA soil survey maps 87% of Park County as well drained — but another 10% drains differently: 5% moderately well drained, 2% excessively drained.
Hiland is the most extensive named soil at 2% of mapped acres, then Fughes-like (2%) and Maysdorf (2%).
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 Park County
Each reading below is measured for Park 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 Park 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 Park County runs about pH 7.2–7.8, 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
MeasuredPark County runs about 117 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredPark County 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 Park County is in
Park County spans 2 EPA Level III ecoregions — Middle Rockies (65%) and Wyoming Basin (35%). 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 Park County
We scored all 1,086 plants against Park County's own USDA zone 5a and its own 117-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 Wyoming profile.
Is it too late to plant in Park County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Apr 29; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 21 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What gets applied to farmland in Park County
USGS estimates 79,249 lb of Glyphosate on Park County farmland in 2019, its largest by weight, ahead of 2,4-d (13,501 lb) and Chlorpyrifos (5,514 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 Park County — and how to grow with it.
We checked the federal record across Park County — 498 documented sites across 7 of the 9 source types we track.
The most significant on record: 4 Superfund sites (none NPL-listed). 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 Park 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 Park County
Closest first, across Park County. Listing isn't leaking, and distance isn't exposure.
- Trail Inn and MotelUnderground Storage Tanks · 4.0 mi
- Mountain View Resort, LLCUnderground Storage Tanks · 4.2 mi
- Wapiti Red BarnUnderground Storage Tanks · 5.6 mi
- CODY, CITY OFPFAS · 6.1 mi
- Energy Distributing CompanyUnderground Storage Tanks · 8.4 mi
- U. S. BUREAU OF RECLAMATIONBrownfields · 8.9 mi
- UnknownMining · 10.9 mi
- Big Goose VeinMining · 11.4 mi
- Butte ClaimMining · 11.4 mi
- Tip Top ClaimMining · 13.5 mi
- Copper KingMining · 13.5 mi
- Hoodoo ClaimMining · 13.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Park 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 Park County.
Total Sites
498
across Park County
Risk Level
Elevated
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
across Park County
Severity Distribution
across Park County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Check your specific parcel in Park 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 Park County average
Your land is one point inside Park County
Everything above resolves to Park County as a whole — one PHZM band and one county frost record, read across 4.4M 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 Park County Average
Park County Average
- ●USDA Zones 5a, averaged across Park County
- ●One soil character for all of Park County
- ●Frost dates read at Park County's scale: May 27 to Sep 21
YOUR Parcel
- ✓Your exact zone, not Park County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Park County
Pull a site-specific report for your exact address in Park County, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Park County averages can't show:
We read public map data around Park County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Park County average
How we know this about Park 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 Park County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Park County
When does frost risk typically end in Park County?
The last hard freeze (28°F) in Park County typically lands around May 27, 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 Jun 17.
How long is the growing season in Park County?
Measured between 28°F hard freezes, Park County sees about 117 frost-free days — roughly May 27 through Sep 21, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 17 to Sep 7, about 82 days.
Is the soil safe to grow vegetables in Park County?
The federal record around Park County is a meaningful one — 498 documented sites, mostly Underground Storage Tanks entries (233), the nearest Underground Storage Tanks record about 4.0 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 gardeners stretch the season in Park County?
With about 117 frost-free days between hard freezes, Park County rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 145 to 173 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 27 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Park County's scale — its 5a band and its 117-day season. Your yard writes its own version of Park 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 Wyoming's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Park County’s own scale
8 of the readings below were taken at Park County's own scale — its own ~117-day span between 28°F freezes, the 3 most extensive soil series mapped here and 498 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Park County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Park County's own 28°F hard-freeze dates and its ~117-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Park CountyUSDA NRCS SSURGO
- 498 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 4.0 miles outFederal environmental registers
- Park County's boundary and the 4,440,981 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~117-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Park County spans, Middle Rockies the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Park County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Wyoming grower plans around — written at state scale, so they stay on the state guidefrom Wyoming
What this page can’t tell you
- How the season shifts across Park County — the ~117 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 Park County's 4,440,981 acreswhy one lot differs from the next →
- Which of those 498 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 Park Countyread your own land →