Washam, Wyoming, sits in USDA hardiness zone 5b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with cabbage, cranberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Washam, 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 Washam 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 Washam — soil, climate, flood, and parcel records. How we handle your address.
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Washam — the short answer
Washam, Wyoming: USDA zone 5b, about 160 days between hard freezes, across 2K acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 3
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~160
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K 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 5b is Washam's average, not your lot's — a low corner or a tree line moves it. Against Washam's 160-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Washam
Each reading below is measured for Washam itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWasham runs about 160 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
MeasuredWasham sits in USDA hardiness zone 5b.
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 Washam is in
Washam sits in the Wyoming Basin — EPA Level III, inside the wider North American Deserts. That is read at Washam's own centroid rather than borrowed from Sweetwater County.
What Grows in Washam
Every plant below cleared Washam's own zone 5b and its 160-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in Washam?
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 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 10 — 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.
What's on the federal record near Washam
Closest first, within ~10 miles of Washam. Listing isn't leaking, and distance isn't exposure.
- UDOT STA # 3436Underground Storage Tanks · 1.2 mi
- Mustang Travel Stop, LLCUnderground Storage Tanks · 1.3 mi
- ELLSWORTHS CONOCO SERVICEUnderground Storage Tanks · 1.3 mi
- DAGGETT SCHOOL DISTRICTUnderground Storage Tanks · 1.6 mi
- SLAUGH'S SINCLAIRUnderground Storage Tanks · 1.7 mi
- VILLA CAFE (OLD STATION)Underground Storage Tanks · 1.7 mi
- MANILA AIRPORTUnderground Storage Tanks · 1.7 mi
- DAGGETT COUNTYUnderground Storage Tanks · 1.8 mi
- U.S.F.S./N.R.A. HEADQUARTERS WAREHOUSEUnderground Storage Tanks · 1.8 mi
- VANCE GRUBBUnderground Storage Tanks · 2.2 mi
- US FOREST SERVICE - LUCERNE VALLEYSuperfund · 5.4 mi
- U.S.F.S./LUCERNE VALLEYUnderground Storage Tanks · 5.7 mi
4 more sites are on the record inside the same radius. See them on the map
Measured from Washam'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 Washam.
Total Sites
18
within ~10 miles of Washam
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Washam
Severity Distribution
within ~10 miles of Washam
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Mine waste leaches heavy metals. Test for lead, arsenic and cadmium before growing food here.
Check your specific parcel in Washam
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 Washam average
Your land is one point inside Washam
Everything above resolves to Washam as a whole — one PHZM band and one 28°F frost record, read across 2K 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 town 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 Washam Average
Washam Average
- ●USDA Zones 5b, averaged across Washam
- ●One soil character for all of Washam
- ●Frost dates read at Washam's scale: May 3 to Oct 10
YOUR Parcel
- ✓Your exact zone, not Washam's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Washam
Pull a site-specific report for your exact address in Washam, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Washam averages can't show:
We read public map data around Washam — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Washam average
How we know this about Washam
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Washam’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 town grain anywhere on this page — there is no town-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 Washam
When does frost risk typically end in Washam?
The last hard freeze (28°F) in Washam typically lands around May 3, 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 24.
When is the first frost in Washam?
The first hard freeze (28°F) in Washam typically arrives around Oct 10, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 26, so the watching starts about Sep 10 — about 160 days after the spring freeze cleared.
How long is the growing season in Washam?
Measured between 28°F hard freezes, Washam sees about 160 frost-free days — roughly May 3 through Oct 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 24 to Sep 26, about 125 days.
Is the soil safe to grow vegetables in Washam?
The federal record around Washam is a meaningful one — 18 documented sites, mostly Underground Storage Tanks entries (14), the nearest Underground Storage Tanks record about 1.2 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 Washam?
From about Sep 10 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 10 (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 10. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Washam's scale — its 5b band and its 160-day season. Your yard writes its own version of Washam'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 Washam’s own scale
6 of the readings below were taken at Washam's own scale — its own ~160-day season between 28°F freezes, the 1,992 acres it covers and 18 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Washam's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Washam's own 28°F hard-freeze dates, about May 3 and Oct 10 and the ~160-day span between themNOAA 1991–2020 Climate Normals
- 18 documented contamination sites on the federal record near Washam, the closest Underground Storage Tanks record about 1.2 miles out from the town centreFederal environmental registers
- Washam's boundary and the 1,992 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~160-day seasonGrowable Ground crop-matching engine
- The ecoregion at Washam's own centroid, the Wyoming BasinUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Washam's 1,992 acres read through its county's SSURGO summaryfrom Sweetwater County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Sweetwater 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 Sweetwater County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Washam's 1,992 acreswhy one lot differs from the next →
- Which side of Washam you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,992 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 1.2 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 Washam-wide figureread your own land →
More in Wyoming
Wider growing context
What grows across WyomingWasham sits outside our named growing regions, so Wyoming as a whole is its closest context here.
Nearby growing guides