Riverton, Wyoming, sits in USDA hardiness zone 4b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Growers here do well with cabbage, cranberry, turkish rocket, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Riverton, 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 Riverton 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 Riverton — soil, climate, flood, and parcel records. How we handle your address.
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Riverton — the short answer
Riverton, Wyoming: USDA zone 4b, about 151 days between hard freezes, across 7K acres of city.
- USDA zone
- 4b
- 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 3
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~151
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 7K 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 4b is Riverton's average, not your lot's — a low corner or a tree line moves it. Against Riverton's 151-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Riverton
Each reading below is measured for Riverton itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRiverton runs about 151 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
MeasuredRiverton sits in USDA hardiness zone 4b.
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 Riverton is in
Riverton sits in the Wyoming Basin — EPA Level III, inside the wider North American Deserts. That is read at Riverton's own centroid rather than borrowed from Fremont County.
What Grows in Riverton
Every plant below cleared Riverton's own zone 4b and its 151-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in Riverton?
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 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 3 — 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's on the federal record near Riverton
Closest first, within ~10 miles of Riverton. Listing isn't leaking, and distance isn't exposure.
- Texaco ServiceUnderground Storage Tanks · 200 ft
- DENTS AUTO AND LIGHT TRUCK REPAIRBrownfields · 300 ft
- Good to Go Store #19Underground Storage Tanks · 350 ft
- Loaf 'N Jug #156Underground Storage Tanks · 400 ft
- Dents Auto and Light Truck RepairUnderground Storage Tanks · 500 ft
- Dean's Tire and BrakeUnderground Storage Tanks · 600 ft
- D J Auto Rentals, Inc.Underground Storage Tanks · 600 ft
- Riverton RCLUnderground Storage Tanks · 600 ft
- Louisiana-Pacific CorporationUnderground Storage Tanks · 600 ft
- Sheldon Dome CampUnderground Storage Tanks · 600 ft
- Totem Construction Company, Inc.Underground Storage Tanks · 600 ft
- Amoco Production CompanyUnderground Storage Tanks · 600 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Riverton'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 Riverton.
Total Sites
233
within ~10 miles of Riverton
Risk Level
Elevated
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Riverton
Severity Distribution
within ~10 miles of Riverton
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Riverton, Nitrate runs higher than the national average — 64 sites within ~10 miles of Riverton. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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 Riverton
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 Riverton average
Your land is one point inside Riverton
Everything above resolves to Riverton as a whole — one PHZM band and one 28°F frost record, read across 7K 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 Riverton Average
Riverton Average
- ●USDA Zones 4b, averaged across Riverton
- ●One soil character for all of Riverton
- ●Frost dates read at Riverton's scale: May 5 to Oct 3
YOUR Parcel
- ✓Your exact zone, not Riverton's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Riverton
Pull a site-specific report for your exact address in Riverton, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Riverton averages can't show:
We read public map data around Riverton — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Riverton average
How we know this about Riverton
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 Riverton’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 Riverton
When does frost risk typically end in Riverton?
The last hard freeze (28°F) in Riverton 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 Riverton?
The first hard freeze (28°F) in Riverton typically arrives around Oct 3, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 19, so the watching starts about Sep 3 — about 151 days after the spring freeze cleared.
How long is the growing season in Riverton?
Measured between 28°F hard freezes, Riverton sees about 151 frost-free days — roughly May 5 through Oct 3, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Sep 19, about 116 days.
Is the soil safe to grow vegetables in Riverton?
The federal record around Riverton is a meaningful one — 233 documented sites, mostly Underground Storage Tanks entries (108), the nearest Underground Storage Tanks record under a tenth of a mile 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 Riverton?
From about Sep 3 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 3 (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 3. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Riverton's scale — its 4b band and its 151-day season. Your yard writes its own version of Riverton'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 Riverton’s own scale
6 of the readings below were taken at Riverton's own scale — its own ~151-day season between 28°F freezes, the 6,629 acres it covers and 233 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Riverton's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Riverton's own 28°F hard-freeze dates, about May 5 and Oct 3 and the ~151-day span between themNOAA 1991–2020 Climate Normals
- 233 documented contamination sites on the federal record near Riverton, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Riverton's boundary and the 6,629 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~151-day seasonGrowable Ground crop-matching engine
- The ecoregion at Riverton's own centroid, the Wyoming BasinUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Riverton's 6,629 acres read through its county's SSURGO summaryfrom Fremont County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Fremont 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 Fremont County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Riverton's 6,629 acreswhy one lot differs from the next →
- Which side of Riverton you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 6,629 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Riverton-wide figureread your own land →
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