Platte County, in Wyoming, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Crops well matched to these conditions include cabbage, cranberry, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Platte 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
Platte County holds more than one microclimate.
Soils and elevations shift across Platte 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 Platte County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Platte County — the short answer
Platte County, Wyoming: USDA zone 5a, about 157 days between hard freezes, across 1.3M acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 5
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 9
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~157
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.3M 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 Platte County's average, not your lot's — a low corner or a tree line moves it. Against Platte County's 157-day season, see what your own ground reads.
Heat in Platte County
Across a year, Platte County accumulates about 2,325 growing degree days above 50°F, about 451 more than the middle Wyoming county — ahead of 21 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 Platte County
Across Platte County, the ground is predominantly Mollisols, where Keeline, Taluce, and Featherlegs are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 7.2–7.9, slightly alkaline. Rainfall drains through hydrologic group A soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
1%
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Platte County
The USDA soil survey maps 85% of Platte County as well drained — but another 9% drains differently: 4% somewhat excessively drained, 4% moderately well drained.
Keeline is the most extensive named soil at 8% of mapped acres, then Taluce (8%) and Featherlegs (6%).
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 Platte County
Each reading below is measured for Platte 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 Platte County are well drained, in hydrologic group A — 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 Platte 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
MeasuredPlatte County runs about 157 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
MeasuredPlatte 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 Platte County is in
Platte County spans 3 EPA Level III ecoregions — High Plains (68%), Southern Rockies (24%) and Northwestern Great Plains (8%). 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 Platte County
We scored all 1,086 plants against Platte County's own USDA zone 5a and its own 157-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 Platte County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 9 — 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 Platte County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Platte County
USGS estimates 18,252 lb of Glyphosate on Platte County farmland in 2019, its largest by weight, ahead of Atrazine (8,776 lb) and 2,4-d (7,784 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 Platte County — and how to grow with it.
We checked the federal record across Platte County — 298 documented sites across 8 of the 9 source types we track.
The most significant on record: 3 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 Platte 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 Platte County
Closest first, across Platte County. Listing isn't leaking, and distance isn't exposure.
- 25-067-19abd01Nitrate · 1.0 mi
- Basins, Inc. - Quarry-May #1Underground Storage Tanks · 1.3 mi
- Joe Johnson CompanyUnderground Storage Tanks · 3.5 mi
- 25-068-09aaa01Nitrate · 3.5 mi
- AMVC SITE 62CAFO · 3.7 mi
- BASIN ELECTRIC POWER COOPERATIVE - LARAMIE RIVER STATIONToxics Release Inventory · 3.9 mi
- Wheatland Travel PlazaUnderground Storage Tanks · 4.0 mi
- 24-067-07baa01Nitrate · 4.1 mi
- Allen's Parts SupplyUnderground Storage Tanks · 4.2 mi
- Wendover Relay StationUnderground Storage Tanks · 4.3 mi
- LARAMIE PEAK MOTORS LLCBrownfields · 4.4 mi
- BOB RUWART MOTORSBrownfields · 4.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Platte 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 Platte County.
Total Sites
298
across Platte County
Risk Level
Elevated
Highest-severity
3 Superfund sites (none NPL-listed)
Severity Distribution
across Platte County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Platte County, two things run higher than the national average across Platte County — CAFO (6 sites) and Nitrate (84 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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 Platte 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 Platte County average
Your land is one point inside Platte County
Everything above resolves to Platte County as a whole — one PHZM band and one county frost record, read across 1.3M 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 Platte County Average
Platte County Average
- ●USDA Zones 5a, averaged across Platte County
- ●One soil character for all of Platte County
- ●Frost dates read at Platte County's scale: May 5 to Oct 9
YOUR Parcel
- ✓Your exact zone, not Platte County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Platte County
Pull a site-specific report for your exact address in Platte County, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Platte County averages can't show:
We read public map data around Platte County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Platte County average
How we know this about Platte 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 Platte County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Platte County
When does frost risk typically end in Platte County?
The last hard freeze (28°F) in Platte County typically lands around May 5, 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 26.
How long is the growing season in Platte County?
Measured between 28°F hard freezes, Platte County sees about 157 frost-free days — roughly May 5 through Oct 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Sep 25, about 122 days.
Is the soil safe to grow vegetables in Platte County?
The federal record around Platte County is a meaningful one — 298 documented sites, mostly Underground Storage Tanks entries (157), the nearest Nitrate record about 1.0 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.
Everything above is measured at Platte County's scale — its 5a band and its 157-day season. Your yard writes its own version of Platte 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 Platte County’s own scale
9 of the readings below were taken at Platte County's own scale — its own ~157-day span between 28°F freezes, the 3 most extensive soil series mapped here and 298 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Platte County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Platte County's own 28°F hard-freeze dates and its ~157-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Platte CountyUSDA NRCS SSURGO
- 298 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 1.0 miles outFederal environmental registers
- Platte County's boundary and the 1,332,132 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~157-day seasonGrowable Ground crop-matching engine
- The 3 ecoregions Platte County spans, High Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Platte County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Platte 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 Platte County — the ~157 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 Platte County's 1,332,132 acreswhy one lot differs from the next →
- Which of those 298 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 Platte Countyread your own land →