Delta, Utah, sits in USDA hardiness zone 6a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
A short list that earns its place here — cabbage, blackberry, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Delta, 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 Delta 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 Delta — soil, climate, flood, and parcel records. How we handle your address.
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Delta — the short answer
Delta, Utah: USDA zone 6a, about 160 days between hard freezes, across 6K acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 8
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~160
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 6K 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 6a is Delta's average, not your lot's — a low corner or a tree line moves it. Against Delta's 160-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Delta
Each reading below is measured for Delta itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDelta 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
MeasuredDelta sits in USDA hardiness zone 6a.
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 Delta is in
Delta sits in the Central Basin and Range — EPA Level III, inside the wider North American Deserts. That is read at Delta's own centroid rather than borrowed from Millard County.
What Grows in Delta
Every plant below cleared Delta's own zone 6a and its 160-day season. Each card opens that plant's Utah profile. How we score.
Is it too late to plant in Delta?
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 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 1 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 8 — 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 Delta
Closest first, within ~10 miles of Delta. Listing isn't leaking, and distance isn't exposure.
- RELADYNE WESTToxics Release Inventory · 1100 ft
- MOUNTAIN VIEWCAFO · 0.8 mi
- CROSSROADS DAIRY LLCCAFO · 0.8 mi
- (C-17- 6) 6cbd- 3Nitrate · 0.9 mi
- HIGHWAY 6 TRUCK STOPUnderground Storage Tanks · 1.0 mi
- DUCKWORTH DAIRYCAFO · 1.0 mi
- MAVERIK # 493Underground Storage Tanks · 1.3 mi
- (C-17- 6)17aaa- 1Nitrate · 1.3 mi
- DELTA COMMUNITY MEDICAL CENTERUnderground Storage Tanks · 1.3 mi
- DELTA COMMUNITY HOSPITALBrownfields · 1.3 mi
- DELTA RALLY STOPUnderground Storage Tanks · 1.3 mi
- REVOLUTION DAIRYCAFO · 1.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Delta'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 Delta.
Total Sites
155
within ~10 miles of Delta
Risk Level
Moderate
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Delta
Severity Distribution
within ~10 miles of Delta
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Delta, two things run higher than the national average within ~10 miles of Delta — CAFO (23 sites) and Nitrate (86 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Delta
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 Delta average
Your land is one point inside Delta
Everything above resolves to Delta as a whole — one PHZM band and one 28°F frost record, read across 6K 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 Delta Average
Delta Average
- ●USDA Zones 6a, averaged across Delta
- ●One soil character for all of Delta
- ●Frost dates read at Delta's scale: May 1 to Oct 8
YOUR Parcel
- ✓Your exact zone, not Delta's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Delta
Pull a site-specific report for your exact address in Delta, Utah — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Delta averages can't show:
We read public map data around Delta — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Delta average
How we know this about Delta
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 Delta’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 Delta
When does frost risk typically end in Delta?
The last hard freeze (28°F) in Delta typically lands around May 1, 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 22.
When is the first frost in Delta?
The first hard freeze (28°F) in Delta typically arrives around Oct 8, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 24, so the watching starts about Sep 8 — about 160 days after the spring freeze cleared.
How long is the growing season in Delta?
Measured between 28°F hard freezes, Delta sees about 160 frost-free days — roughly May 1 through Oct 8, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 22 to Sep 24, about 125 days.
Is the soil safe to grow vegetables in Delta?
The federal record around Delta shows 155 documented sites, mostly Nitrate entries (86), the nearest Toxics Release Inventory record about 0.2 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Delta?
From about Sep 8 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 8 (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 8. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Delta's scale — its 6a band and its 160-day season. Your yard writes its own version of Delta'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 Delta’s own scale
6 of the readings below were taken at Delta's own scale — its own ~160-day season between 28°F freezes, the 5,517 acres it covers and 155 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Delta's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Delta's own 28°F hard-freeze dates, about May 1 and Oct 8 and the ~160-day span between themNOAA 1991–2020 Climate Normals
- 155 documented contamination sites on the federal record near Delta, the closest Toxics Release Inventory record about 0.2 miles out from the town centreFederal environmental registers
- Delta's boundary and the 5,517 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~160-day seasonGrowable Ground crop-matching engine
- The ecoregion at Delta's own centroid, the Central Basin and RangeUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Delta's 5,517 acres read through its county's SSURGO summaryfrom Millard County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Millard County
- The growing challenges every Utah grower plans around — written at state scale, so they stay on the state guidefrom Utah
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Millard County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Delta's 5,517 acreswhy one lot differs from the next →
- Which side of Delta you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 5,517 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory 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 Delta-wide figureread your own land →
More in Utah
Wider growing context
What grows across UtahDelta sits outside our named growing regions, so Utah as a whole is its closest context here.
Nearby growing guides