Four Square Mile, Colorado, 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.
Reliable performers under these conditions include cabbage, blackberry, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Four Square Mile, 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 Four Square Mile 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 Four Square Mile — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Four Square Mile — the short answer
Four Square Mile, Colorado: USDA zone 6a, about 177 days between hard freezes, across 2K acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 24
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 18
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~177
- 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 6a is Four Square Mile's average, not your lot's — a low corner or a tree line moves it. Against Four Square Mile's 177-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Four Square Mile
Each reading below is measured for Four Square Mile itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFour Square Mile runs about 177 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
MeasuredFour Square Mile 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 Four Square Mile is in
Four Square Mile sits in the High Plains — EPA Level III, inside the wider Great Plains. That is read at Four Square Mile's own centroid rather than borrowed from Arapahoe County.
What Grows in Four Square Mile
Every plant below cleared Four Square Mile's own zone 6a and its 177-day season. Each card opens that plant's Colorado profile. How we score.
Is it too late to plant in Four Square Mile?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 18 — 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 Four Square Mile
Closest first, within ~10 miles of Four Square Mile. Listing isn't leaking, and distance isn't exposure.
- The Ceco CorpUnderground Storage Tanks · 750 ft
- Public Service SE MetroUnderground Storage Tanks · 850 ft
- PUBLIC SERVICE CO - VALENTIA SRVC CNTRBrownfields · 1100 ft
- SILVER ANVIL ENGINEERING CORPBrownfields · 1100 ft
- THE GREEN MONSTER RECYCLINGBrownfields · 1100 ft
- R G Dameron JrUnderground Storage Tanks · 1200 ft
- SavATree LLCUnderground Storage Tanks · 1400 ft
- Reid Management & MaintenanceUnderground Storage Tanks · 1400 ft
- Rogers Concrete IncUnderground Storage Tanks · 1400 ft
- Haselden Construction IncUnderground Storage Tanks · 1500 ft
- Perky Pets ProductsUnderground Storage Tanks · 1600 ft
- Supreme Transportation IncUnderground Storage Tanks · 1700 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Four Square Mile'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 Four Square Mile.
Total Sites
5,050
within ~10 miles of Four Square Mile
Risk Level
High
Highest-severity
42 Superfund sites
Sources Checked
within ~10 miles of Four Square Mile
Severity Distribution
within ~10 miles of Four Square Mile
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 Four Square Mile
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 Four Square Mile average
Your land is one point inside Four Square Mile
Everything above resolves to Four Square Mile 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 Four Square Mile Average
Four Square Mile Average
- ●USDA Zones 6a, averaged across Four Square Mile
- ●One soil character for all of Four Square Mile
- ●Frost dates read at Four Square Mile's scale: Apr 24 to Oct 18
YOUR Parcel
- ✓Your exact zone, not Four Square Mile's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Four Square Mile
Pull a site-specific report for your exact address in Four Square Mile, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Four Square Mile averages can't show:
We read public map data around Four Square Mile — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Four Square Mile average
How we know this about Four Square Mile
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 Four Square Mile’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 Four Square Mile
When does frost risk typically end in Four Square Mile?
The last hard freeze (28°F) in Four Square Mile typically lands around Apr 24, 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 15.
When is the first frost in Four Square Mile?
The first hard freeze (28°F) in Four Square Mile typically arrives around Oct 18, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 4, so the watching starts about Sep 18 — about 177 days after the spring freeze cleared.
How long is the growing season in Four Square Mile?
Measured between 28°F hard freezes, Four Square Mile sees about 177 frost-free days — roughly Apr 24 through Oct 18, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 15 to Oct 4, about 142 days.
Is the soil safe to grow vegetables in Four Square Mile?
The federal record around Four Square Mile runs heavier than most — 5,050 documented sites, mostly Underground Storage Tanks entries (2,788), the nearest Underground Storage Tanks record about 0.1 miles out — 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.
How do I protect my plants from frost in Four Square Mile?
From about Sep 18 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 18 (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 18. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Four Square Mile's scale — its 6a band and its 177-day season. Your yard writes its own version of Four Square Mile'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 Four Square Mile’s own scale
6 of the readings below were taken at Four Square Mile's own scale — its own ~177-day season between 28°F freezes, the 1,729 acres it covers and 5,050 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Four Square Mile's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Four Square Mile's own 28°F hard-freeze dates, about Apr 24 and Oct 18 and the ~177-day span between themNOAA 1991–2020 Climate Normals
- 5,050 documented contamination sites on the federal record near Four Square Mile, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Four Square Mile's boundary and the 1,729 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~177-day seasonGrowable Ground crop-matching engine
- The ecoregion at Four Square Mile's own centroid, the High PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Four Square Mile's 1,729 acres read through its county's SSURGO summaryfrom Arapahoe County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Arapahoe County
- The growing challenges every Colorado grower plans around — written at state scale, so they stay on the state guidefrom Colorado
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Arapahoe County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Four Square Mile's 1,729 acreswhy one lot differs from the next →
- Which side of Four Square Mile you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,729 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Four Square Mile-wide figureread your own land →