Niobrara County, in Wyoming, sits in USDA hardiness zone 5a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
A short list that earns its place here — potato, indian paintbrush, cottonwood, and rhubarb — with any one site's soil, sun, and drainage making the final cut.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Niobrara County holds more than one microclimate.
Soils and elevations shift across Niobrara County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
5a
Last Hard Freeze (28°F)
Apr 25
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Oct 15
County normal — light frosts arrive a few weeks earlier
County Area
1.7M acres
Hardiness Zone Range
Zone maps are averages across Niobrara County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Niobrara County
Across Niobrara County, the ground is predominantly Entisols, where Theedle, Kishona, and Shingle are the most extensive named soil series. The soil is generally well drained with a loam surface. Topsoil pH runs about 7.2–7.8, slightly alkaline. Rainfall drains through hydrologic group D soils.
Soil order
Entisols
Drainage
Well drained
Prime farmland
0%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
What Grows in Niobrara County
Plants matched to Niobrara County's USDA zones 5a — each links to its full growing profile.
Is it too late to plant in Niobrara 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 Mar 28; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 25 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 15 — 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.
Growing Challenges in Wyoming
What an experienced grower plans around here — each one has a move.
Extremely short growing season (60-90 frost-free days)
At 60-90 frost-free days, a greenhouse or high tunnel isn't optional equipment — it's where the season actually happens.
Very low rainfall requires irrigation
Drip irrigation under mulch makes scarce water go the distance — build the system before the first bed.
Persistent high winds desiccate and damage plants
Windbreaks first, plants second — a sheltered bed loses a fraction of the moisture an exposed one does.
For cultivar selection, pest pressure, and planting-time guidance specific to Wyoming, the University of Wyoming Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Niobrara County — and how to grow with it.
We checked the federal record across Niobrara County — 143 documented sites across 6 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 Niobrara 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.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Total Sites
143
across Niobrara County
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
across Niobrara County
Severity Distribution
across Niobrara County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Niobrara County, Nitrate runs higher than the national average — 96 sites nearby. That's not a problem with your land — it's information about it.
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 Niobrara County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Niobrara County Average
- ●USDA Zones 5a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Niobrara County
Pull a site-specific report for your exact address in Niobrara County, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Niobrara County, Wyoming
- USDA Hardiness Zones: 5a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Apr 25 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Oct 15 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~173 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 1.7M acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Niobrara County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Niobrara County, Wyoming?
Niobrara County sits in USDA hardiness zone 5a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Niobrara 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 Mar 28; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 25 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 15 — 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.
When does frost risk typically end in Niobrara County?
The last hard freeze (28°F) in Niobrara County typically lands around Apr 25, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Niobrara County?
Measured between 28°F hard freezes, Niobrara County sees about 173 frost-free days — roughly Apr 25 through Oct 15, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Niobrara County?
Niobrara County's zone 5a supports a wide range — strong performers include Potato, Indian Paintbrush, Cottonwood, Rhubarb, and Chokecherry. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Niobrara County, really?
Officially, Niobrara County sits in USDA zone 5a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Niobrara County?
The federal record around Niobrara County shows 143 documented sites — 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.
Just moved to Niobrara County — what should I know before planting?
Start with three facts. Niobrara County sits in USDA zone 5a, which sets what survives winter; the last 28°F hard freeze typically clears around Apr 25, with about 173 frost-free days to work with (NOAA 1991–2020 climate normals); and 143 documented sites sit on the federal record — a typical footprint for a growing area, worth a look on the contamination map before food beds. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Niobrara County average. Your yard writes its own version — 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.