Wyoming spans USDA hardiness zones 3b-6a, with a growing season of about 151 frost-free days — a working season long enough for the classics, short enough that timing around frost stays part of the craft.
Those zone numbers rest on 6-20 inches of annual rainfall, a median of roughly 1,866 growing-degree days (base 50°F), and about 2,500 winter chill hours for tree fruit — the measurements that do the deciding. The prevailing soils — sandy loam, clay, alkaline, and volcanic ash — differ most in how they drain, which is exactly where crop success is usually decided. Between High Plains, Bighorn Basin, and Jackson Hole & Teton Valley, the growing rules shift enough that zone and frost advice only turns precise once you pick your region. Among the crops suited to this profile: potato, indian paintbrush, cottonwood, and rhubarb. The site-level story — soil, sun, drainage — decides the rest.
Grounded inUSDA PHZM•NOAA Climate Normals•USDA NRCS SSURGO•GDD (PRISM 1991-2020 normals)•Chill hours (PRISM 1991-2020 normals)•USDA hardiness sub-region map•EPA FRS•USDA PLANTS•Growable Ground suitability scoring
Wyoming spans zones 3b-6a, but your yard sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Wyoming — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Distinct growing regions within Wyoming — each has its own zones, soils, and signature crops.
Wyoming: USDA zones 3b-6a, 79–166 frost-free days depending on the county, 23 counties.
The middle half of this state’s counties. Tender transplants usually wait 2–3 weeks past the last hard freeze. The shortest-season figure is Wyoming's own county record — Teton County's measured 28°F normal, not a modeled floor.
Zone 3b-6a is Wyoming's average, not your lot's — a low corner or a tree line moves it. Against Wyoming's 151-day season, see what your own ground reads.
One answer for Wyoming averages 23 counties whose growing seasons are 87 days apart — from 79 frost-free days in Teton County to 166 in Big Horn County. That is the same state, measured the same way, in the same years. Which end of it your county sits nearer decides what finishes before the first hard freeze.
The middle half of 23 counties runs 136–155 days, with a median of 151 days — a 87-day span end to end.
Measured across 23 counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. A county with no record of its own is absent from the range rather than counted as zero — nothing here is interpolated to the state. Your own site sits somewhere inside this range; a parcel report resolves where.
The middle half of Wyoming runs 136–155 frost-free days, and 9 of its 23 counties sit outside that — 5 on the short side, 4 on the long. A statewide planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 136 frost-free days
5 counties
3 of 5 shown
The end of the state that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
136–155 frost-free days
14 counties
0 of 14 shown
The middle half of the state, and the part a single statewide date describes well.
Over 155 frost-free days
4 counties
3 of 4 shown
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its own 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a yard within its county as well — which is the part only your address resolves.
The soil types that dominate Wyoming — how each drains decides more about crop success than almost anything else. Tap any soil to learn what it is and how to work with it. Each photo is a representative profile of that soil type; the named series is where it was documented, which is often another state.
Drainage
Fast. The sand fraction opens the soil up, so water moves through the root zone quickly and the surface rarely stays soggy. The trade is that nutrients ride out with the water.
What thrives
Root crops love it — carrots, potatoes, radishes, and onions size up cleanly in ground they can push through. Melons, sweet potatoes, asparagus, and most herbs appreciate the warmth and the drainage.
Drainage
Slow. Water enters clay reluctantly and leaves it the same way, so wet springs keep it cold and unworkable longer than lighter soils.
What thrives
Once established, heavy feeders prosper — brassicas, beans, corn, and many fruit trees ride clay’s nutrient supply and summer moisture reserve. Daylilies, roses, and prairie perennials handle it without complaint.
Ground with pH above neutral — the norm in dry country, where rainfall never fully leaches the calcium and other bases out of the profile. The chemistry governs which nutrients roots can actually reach.
Drainage
Alkalinity is chemistry, not texture — these soils range from fast sands to slow clays. What they share is the high pH, not a drainage habit.
What thrives
A long roster of garden plants is comfortable above pH 7: asparagus, beets, spinach, brassicas, figs, pomegranates, lavender, and most Mediterranean herbs among them.
Drainage
Excellent and unusual: ash soils drain freely yet hold remarkable amounts of plant-available water in their porous structure — the best of both habits.
What thrives
Volcanic regions grow celebrated crops the world over: orchards, berries, vegetables, coffee, and wine grapes all prosper on ash-derived soils.
Soil data: USDA NRCS SSURGO · Soil types explained
Plants well-suited to Wyoming's climate, soils, and growing season — each links to its full growing profile.
Usually not — gardeners here simply switch what goes in the ground as the season moves. Across Wyoming, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near May 6, with the middle half of counties between May 4 and May 13 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Sep 30 and Oct 7 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
The plants Wyoming put its name on — cultural emblems, not growing recommendations.
Indian paintbrush
Castilleja linariifolia
Designated 1917.
Plains cottonwood
Populus deltoides monilifera
Designated 1947.
Plants the USDA PLANTS Database documents as native and present in Wyoming — a real per-state range, not just a zone match. Ordered by how closely each plant’s published hardiness range matches Wyoming’s zones 3b-6a, so this is a shortlist by climate fit, not a ranking of which plants matter most here. Presence is statewide, so a plant may still be uncommon in your specific county; your state’s Cooperative Extension or a native-plant society is the local authority.
US-native plants whose hardiness range overlaps Wyoming’s USDA zones 3b-6a but which USDA PLANTS doesn’t map to a single state range here. Zone overlap is a starting filter, not a range map.
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 Wyoming — and how to grow with it.
We checked the federal record across Wyoming — 10,910 documented sites across 8 of the 9 source types we track.
The most significant on record: 64 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Wyoming carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Severity Distribution
across Wyoming
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Wyoming, Nitrate runs higher than the national average — 4,750 sites across Wyoming. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Everything above resolves to Wyoming as a whole — a state whose own counties record seasons 87 days apart, and hardiness across zones 3b-6a. Your parcel sits at one point in that range, not in the middle of it. 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 state 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 statewide average.
State averages sketch the shape. Your soil, sun exposure, drainage, and microclimate decide what actually takes. Pull a site-specific report for your exact parcel.
Enter your address. We read your soil, sun, drainage, and frost dates, then score 1,086 plants against the real conditions on your land.
Three things about your lot that Wyoming averages can't show:
We read public map data around Wyoming — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Wyoming average
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read per county and aggregated to the state band; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each county’s own record; rainfall from NOAA Climate Normals; soils from USDA NRCS SSURGO; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above. Where a county carries no record of its own, it is absent from the figure rather than filled in.
Wyoming spans USDA hardiness zones 3b-6a — which is to say winter's coldest night runs from about −35°F to −5°F depending where in Wyoming you are, averaged over 1991–2020 (USDA PHZM 2023).
Usually not — gardeners here simply switch what goes in the ground as the season moves. Across Wyoming, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near May 6, with the middle half of counties between May 4 and May 13 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Sep 30 and Oct 7 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
Across Wyoming, the middle half of counties see their last hard freeze (28°F) between about May 4 and May 13, with a county median near May 6 (NOAA 1991–2020 climate normals). 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 27.
Measured between 28°F hard freezes, growing seasons across Wyoming's counties mostly run about 139 to 155 days, with a county median near 151 (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.
Wyoming's zones 3b-6a support 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.
Officially, Wyoming spans USDA zones 3b-6a (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 1,086 plants against what's actually there.
The federal record across Wyoming runs heavier than most — 10,910 documented sites, mostly Nitrate entries (4,750) — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Start with three facts. Wyoming spans USDA zones 3b-6a, which sets what survives winter; last hard freezes range from about May 4 to May 13 across its counties (NOAA 1991–2020 climate normals); and 10,910 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything above is measured at Wyoming's scale — its 3b-6a band and its 151-day season. Your yard writes its own version of Wyoming's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
6 of the readings below were taken at Wyoming's own scale — the full zone 3b-6a span inside its borders, the 4 soil types that dominate its ground and 10,910 documented sites on its federal record; anything it cannot resolve at this scale is named below.
Measured here
What this page can’t tell you
Explore growing conditions by city or town in Wyoming.
