Westminster, Colorado, sits in USDA hardiness zone 6a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with cabbage, hazelnut, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Westminster, 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 Westminster 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 Westminster — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Westminster — the short answer
Westminster, Colorado: USDA zone 6a, about 184 days between hard freezes, across 20K acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 19
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~184
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 20K 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 Westminster's average, not your lot's — a low corner or a tree line moves it. Against Westminster's 184-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Westminster
Each reading below is measured for Westminster itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWestminster runs about 184 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
MeasuredWestminster 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 Westminster is in
Westminster sits in the High Plains — EPA Level III, inside the wider Great Plains. That is read at Westminster's own centroid, and it is not what its county reads: Jefferson County is mostly Southern Rockies. The wider page above you is answering a different question about different ground.
What Grows in Westminster
Every plant below cleared Westminster's own zone 6a and its 184-day season. Each card opens that plant's Colorado profile. How we score.
Is it too late to plant in Westminster?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 22; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 19 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 20 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Westminster
Closest first, within ~10 miles of Westminster. Listing isn't leaking, and distance isn't exposure.
- CITY OF WESTMINSTER PARKS OPERATIONS CTRBrownfields · 0.7 mi
- Trend Homes Of ColoradoUnderground Storage Tanks · 0.7 mi
- Anderson Amoco Food ShopsUnderground Storage Tanks · 0.7 mi
- 7-Eleven #34036Underground Storage Tanks · 0.8 mi
- CENTURA HEALTH CHURCH RANCH EMERGENCY DEPARTMENTBrownfields · 0.8 mi
- The Courses At Hyland Hills - Cart BarnUnderground Storage Tanks · 0.9 mi
- POWERSECURE - WALMART # 2223Brownfields · 0.9 mi
- WALNUT CREEK DENTAL GROUP AND ORTHODONTICSBrownfields · 0.9 mi
- PETCO #2482Brownfields · 0.9 mi
- CST Metro LLC DBA Corner Store #1146Underground Storage Tanks · 0.9 mi
- A CARING DOCTOR (MINNESOTA) P A DBA BANFIELD PET HOSPITAL #1458Brownfields · 0.9 mi
- ASPEN DENTALBrownfields · 1.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Westminster'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 Westminster.
Sources Checked
within ~10 miles of Westminster
Severity Distribution
within ~10 miles of Westminster
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 Westminster
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 Westminster average
Your land is one point inside Westminster
Everything above resolves to Westminster as a whole — one PHZM band and one 28°F frost record, read across 20K 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 Westminster Average
Westminster Average
- ●USDA Zones 6a, averaged across Westminster
- ●One soil character for all of Westminster
- ●Frost dates read at Westminster's scale: Apr 19 to Oct 20
YOUR Parcel
- ✓Your exact zone, not Westminster's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Westminster
Pull a site-specific report for your exact address in Westminster, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Westminster averages can't show:
We read public map data around Westminster — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Westminster average
How we know this about Westminster
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 Westminster’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 Westminster
When does frost risk typically end in Westminster?
The last hard freeze (28°F) in Westminster typically lands around Apr 19, 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 10.
When is the first frost in Westminster?
The first hard freeze (28°F) in Westminster typically arrives around Oct 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 6, so the watching starts about Sep 20 — about 184 days after the spring freeze cleared.
How long is the growing season in Westminster?
Measured between 28°F hard freezes, Westminster sees about 184 frost-free days — roughly Apr 19 through Oct 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 10 to Oct 6, about 149 days.
Is the soil safe to grow vegetables in Westminster?
The federal record around Westminster runs heavier than most — 3,182 documented sites, mostly Underground Storage Tanks entries (1,704), the nearest Brownfields record about 0.7 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 Westminster?
From about Sep 20 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 20 (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 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Westminster's scale — its 6a band and its 184-day season. Your yard writes its own version of Westminster'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 Westminster’s own scale
6 of the readings below were taken at Westminster's own scale — its own ~184-day season between 28°F freezes, the 20,236 acres it covers and 3,182 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Westminster's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Westminster's own 28°F hard-freeze dates, about Apr 19 and Oct 20 and the ~184-day span between themNOAA 1991–2020 Climate Normals
- 3,182 documented contamination sites on the federal record near Westminster, the closest Brownfields record about 0.7 miles out from the town centreFederal environmental registers
- Westminster's boundary and the 20,236 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~184-day seasonGrowable Ground crop-matching engine
- Westminster sits in the High Plains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Westminster's 20,236 acres read through its county's SSURGO summaryfrom Jefferson County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Jefferson 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 Jefferson County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Westminster's 20,236 acreswhy one lot differs from the next →
- Which side of Westminster you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 20,236 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.7 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 Westminster-wide figureread your own land →
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