Powell, Wyoming, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
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 Powell, 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 Powell 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 Powell — soil, climate, flood, and parcel records. How we handle your address.
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Powell — the short answer
Powell, Wyoming: USDA zone 5a, about 155 days between hard freezes, across 3K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~155
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 3K 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 Powell's average, not your lot's — a low corner or a tree line moves it. Against Powell's 155-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Powell
Each reading below is measured for Powell itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredPowell 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
MeasuredPowell 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 Powell is in
Powell sits in the Wyoming Basin — EPA Level III, inside the wider North American Deserts. That is read at Powell's own centroid, and it is not what its county reads: Park County is mostly Middle Rockies. The wider page above you is answering a different question about different ground.
What Grows in Powell
Every plant below cleared Powell'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 Powell?
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 4; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 4 — 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 Powell
Closest first, within ~10 miles of Powell. Listing isn't leaking, and distance isn't exposure.
- Northwest Community CollegeUnderground Storage Tanks · 1100 ft
- NORTHWEST COLLEGEBrownfields · 1200 ft
- E and J EnterprisesUnderground Storage Tanks · 1200 ft
- JOHNSONS OIL & WATER SERVICEBrownfields · 1800 ft
- PARK COUNTY SCHOOL DISTRICT NO. 1 POWELL MIDDLE SCHOOLBrownfields · 2400 ft
- COUNTY SCHOOL DISTRICT #1 (PHS GYMNASIUM)Brownfields · 2400 ft
- Kraus Tank ServiceUnderground Storage Tanks · 0.5 mi
- Ron's ExxonUnderground Storage Tanks · 0.5 mi
- Clay's Electrical Service, Inc.Underground Storage Tanks · 0.5 mi
- B and L Auto PartsUnderground Storage Tanks · 0.6 mi
- Elk Basin FieldUnderground Storage Tanks · 0.6 mi
- Conoco, Inc. - South Elk BasinUnderground Storage Tanks · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Powell'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 Powell.
Total Sites
170
within ~10 miles of Powell
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Powell
Severity Distribution
within ~10 miles of Powell
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Powell, Nitrate runs higher than the national average — 52 sites within ~10 miles of Powell. 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 Powell
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 Powell average
Your land is one point inside Powell
Everything above resolves to Powell as a whole — one PHZM band and one 28°F frost record, read across 3K 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 Powell Average
Powell Average
- ●USDA Zones 5a, averaged across Powell
- ●One soil character for all of Powell
- ●Frost dates read at Powell's scale: May 2 to Oct 4
YOUR Parcel
- ✓Your exact zone, not Powell's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Powell
Pull a site-specific report for your exact address in Powell, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Powell averages can't show:
We read public map data around Powell — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Powell average
How we know this about Powell
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 Powell’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 Powell
When does frost risk typically end in Powell?
The last hard freeze (28°F) in Powell typically lands around May 2, 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 23.
When is the first frost in Powell?
The first hard freeze (28°F) in Powell typically arrives around Oct 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 20, so the watching starts about Sep 4 — about 155 days after the spring freeze cleared.
How long is the growing season in Powell?
Measured between 28°F hard freezes, Powell sees about 155 frost-free days — roughly May 2 through Oct 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 23 to Sep 20, about 120 days.
Is the soil safe to grow vegetables in Powell?
The federal record around Powell is a meaningful one — 170 documented sites, mostly Underground Storage Tanks entries (77), 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 Powell?
From about Sep 4 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 4 (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 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Powell's scale — its 5a band and its 155-day season. Your yard writes its own version of Powell'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 Powell’s own scale
6 of the readings below were taken at Powell's own scale — its own ~155-day season between 28°F freezes, the 2,744 acres it covers and 170 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Powell's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Powell's own 28°F hard-freeze dates, about May 2 and Oct 4 and the ~155-day span between themNOAA 1991–2020 Climate Normals
- 170 documented contamination sites on the federal record near Powell, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Powell's boundary and the 2,744 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~155-day seasonGrowable Ground crop-matching engine
- Powell sits in the Wyoming Basin — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Powell's 2,744 acres read through its county's SSURGO summaryfrom Park County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Park 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 Park County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Powell's 2,744 acreswhy one lot differs from the next →
- Which side of Powell you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,744 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 Powell-wide figureread your own land →
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