Casper, Wyoming, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Well-matched crops include cabbage, cranberry, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Casper, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Casper lot. 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 Casper — soil, climate, flood, and parcel records. How we handle your address.
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Casper — the short answer
Casper, Wyoming: USDA zone 5a, about 155 days between hard freezes, across 17K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~155
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 17K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 Casper's average, not your lot's — a low corner or a tree line moves it. Against Casper's 155-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Casper
Each reading below is measured for Casper itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCasper runs about 155 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
MeasuredCasper 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 Casper is in
Casper sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Casper's own centroid, and it is not what its county reads: Natrona County is mostly Wyoming Basin. The wider page above you is answering a different question about different ground.
What Grows in Casper
Every plant below cleared Casper's own zone 5a and its 155-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in Casper?
Rarely: the season closes in stages, not all at once, and each stage has its crops. 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 7 — 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.
What's on the federal record near Casper
Closest first, within ~10 miles of Casper. Listing isn't leaking, and distance isn't exposure.
- Max and Rod StalkupUnderground Storage Tanks · 1200 ft
- Bi-Rite Drug and Package LiquorUnderground Storage Tanks · 1500 ft
- Colliseum Motor CompanyUnderground Storage Tanks · 1500 ft
- COLLISEUM MOTOR CO.Brownfields · 1500 ft
- CASPER DRY CLEANERSBrownfields · 1600 ft
- Northern Utilities, Inc.Underground Storage Tanks · 1800 ft
- BT Building (Formerly Barnard Building)Underground Storage Tanks · 1900 ft
- REED'S AUTOMOTIVE & CUSTOM EXHAUSTBrownfields · 2000 ft
- Jerre's Muffler ShopUnderground Storage Tanks · 2000 ft
- City of Casper - Nicolaysen Art MuseumUnderground Storage Tanks · 2100 ft
- NATRONA COUNTY HIGH SCHOOLBrownfields · 2200 ft
- Natrona County High SchoolUnderground Storage Tanks · 2200 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Casper'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 Casper.
Sources Checked
within ~10 miles of Casper
Severity Distribution
within ~10 miles of Casper
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •TRI facilities report what they release. Check the wind — downwind beds catch more of it.
Check your specific parcel in Casper
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 Casper average
Your land is one point inside Casper
Everything above resolves to Casper as a whole — one PHZM band and one 28°F frost record, read across 17K 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 city 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 local average.
Your Lot vs the Casper Average
Casper Average
- ●USDA Zones 5a, averaged across Casper
- ●One soil character for all of Casper
- ●Frost dates read at Casper's scale: May 5 to Oct 7
YOUR Parcel
- ✓Your exact zone, not Casper's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Casper
Pull a site-specific report for your exact address in Casper, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Casper averages can't show:
We read public map data around Casper — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Casper average
How we know this about Casper
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Casper’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Casper
When does frost risk typically end in Casper?
The last hard freeze (28°F) in Casper 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.
When is the first frost in Casper?
The first hard freeze (28°F) in Casper typically arrives around Oct 7, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 23, so the watching starts about Sep 7 — about 155 days after the spring freeze cleared.
How long is the growing season in Casper?
Measured between 28°F hard freezes, Casper sees about 155 frost-free days — roughly May 5 through Oct 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Sep 23, about 120 days.
Is the soil safe to grow vegetables in Casper?
The federal record around Casper is a meaningful one — 809 documented sites, mostly Underground Storage Tanks entries (452), the nearest Underground Storage Tanks record about 0.2 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 I protect my plants from frost in Casper?
From about Sep 7 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 7 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 7. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Casper's scale — its 5a band and its 155-day season. Your yard writes its own version of Casper's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Casper’s own scale
6 of the readings below were taken at Casper's own scale — its own ~155-day season between 28°F freezes, the 17,122 acres it covers and 809 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Casper's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Casper's own 28°F hard-freeze dates, about May 5 and Oct 7 and the ~155-day span between themNOAA 1991–2020 Climate Normals
- 809 documented contamination sites on the federal record near Casper, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Casper's boundary and the 17,122 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~155-day seasonGrowable Ground crop-matching engine
- Casper sits in the Northwestern Great Plains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Casper's 17,122 acres read through its county's SSURGO summaryfrom Natrona County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Natrona County
- The growing challenges every Wyoming grower plans around — written at state scale, so they stay on the state guidefrom Wyoming
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Natrona County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Casper's 17,122 acreswhy one lot differs from the next →
- Which side of Casper you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 17,122 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Casper-wide figureread your own land →
More in Wyoming
Wider growing context
What grows across WyomingCasper sits outside our named growing regions, so Wyoming as a whole is its closest context here.
Nearby growing guides