Newcastle, Wyoming, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Expect cabbage, cranberry, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Newcastle, 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 Newcastle 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 Newcastle — soil, climate, flood, and parcel records. How we handle your address.
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Newcastle — the short answer
Newcastle, Wyoming: USDA zone 5a, about 158 days between hard freezes, across 2K 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 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~158
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City 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 5a is Newcastle's average, not your lot's — a low corner or a tree line moves it. Against Newcastle's 158-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Newcastle
Each reading below is measured for Newcastle itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredNewcastle runs about 158 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
MeasuredNewcastle 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 Newcastle is in
Newcastle sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Newcastle's own centroid rather than borrowed from Weston County.
What Grows in Newcastle
Every plant below cleared Newcastle's own zone 5a and its 158-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in Newcastle?
Usually not — gardeners here simply switch what goes in the ground as the season moves. 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 10 — 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 Newcastle
Closest first, within ~10 miles of Newcastle. Listing isn't leaking, and distance isn't exposure.
- Babe's Station and CaféUnderground Storage Tanks · 300 ft
- Loaf 'N Jug #167Underground Storage Tanks · 700 ft
- Rich Brothers Servicing, Inc.Underground Storage Tanks · 700 ft
- 307 AUTO REPAIRBrownfields · 800 ft
- WY Department of TransportationUnderground Storage Tanks · 1400 ft
- 4-Way Gas-N-GoUnderground Storage Tanks · 2200 ft
- POPE & TALBOT INCBrownfields · 2200 ft
- Yesway 1182 (Former Fresh Start #11)Underground Storage Tanks · 2300 ft
- 45-061-29aca01Nitrate · 2300 ft
- DIXON BROS INCBrownfields · 2400 ft
- True Oil Company/Clareton, WyomingUnderground Storage Tanks · 2500 ft
- Black Hills PlumbingUnderground Storage Tanks · 2500 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Newcastle'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 Newcastle.
Total Sites
72
within ~10 miles of Newcastle
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Newcastle
Severity Distribution
within ~10 miles of Newcastle
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.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Newcastle
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 Newcastle average
Your land is one point inside Newcastle
Everything above resolves to Newcastle 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 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 Newcastle Average
Newcastle Average
- ●USDA Zones 5a, averaged across Newcastle
- ●One soil character for all of Newcastle
- ●Frost dates read at Newcastle's scale: May 5 to Oct 10
YOUR Parcel
- ✓Your exact zone, not Newcastle's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Newcastle
Pull a site-specific report for your exact address in Newcastle, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Newcastle averages can't show:
We read public map data around Newcastle — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Newcastle average
How we know this about Newcastle
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 Newcastle’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 Newcastle
When does frost risk typically end in Newcastle?
The last hard freeze (28°F) in Newcastle 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 Newcastle?
The first hard freeze (28°F) in Newcastle 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 158 days after the spring freeze cleared.
How long is the growing season in Newcastle?
Measured between 28°F hard freezes, Newcastle sees about 158 frost-free days — roughly May 5 through Oct 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Sep 26, about 123 days.
Is the soil safe to grow vegetables in Newcastle?
The federal record around Newcastle is a meaningful one — 72 documented sites, mostly Underground Storage Tanks entries (35), 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 Newcastle?
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 Newcastle's scale — its 5a band and its 158-day season. Your yard writes its own version of Newcastle'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 Newcastle’s own scale
6 of the readings below were taken at Newcastle's own scale — its own ~158-day season between 28°F freezes, the 1,639 acres it covers and 72 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Newcastle's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Newcastle's own 28°F hard-freeze dates, about May 5 and Oct 10 and the ~158-day span between themNOAA 1991–2020 Climate Normals
- 72 documented contamination sites on the federal record near Newcastle, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Newcastle's boundary and the 1,639 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~158-day seasonGrowable Ground crop-matching engine
- The ecoregion at Newcastle's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Newcastle's 1,639 acres read through its county's SSURGO summaryfrom Weston County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Weston 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 Weston County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Newcastle's 1,639 acreswhy one lot differs from the next →
- Which side of Newcastle you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,639 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 Newcastle-wide figureread your own land →
More in Wyoming
Wider growing context
What grows across WyomingNewcastle sits outside our named growing regions, so Wyoming as a whole is its closest context here.
Nearby growing guides