The Front Range spans USDA hardiness zones 5a-6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Colorado's high, dry urban corridor at the foot of the Rockies — intense sun, alkaline soils, and a short season that rewards cold-hardy, drought-wise gardening. On paper, tomato, colorado blue spruce, apple, and raspberry all suit these conditions — on the ground, soil, sun, and drainage make the final call.
The Front Range spans Colorado.
Your yard isn't all of the Front Range.
The Front Range spans USDA zones 5a-6a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Front Range — soil, climate, flood, and parcel records. How we handle your address.
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The Front Range — the short answer
The Front Range: USDA zones 5a-6a, 139–184 frost-free days depending where in it you stand, in Colorado.
- USDA zones
- 5a-6a
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 139 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Larimer County
- Counties
- 11
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. The season figure is this region's own record, measured across its 11 member counties, not a state or national average.
Hardiness Zone Range
The Front Range is not one growing season
One answer for the Front Range averages 11 counties whose growing seasons are 45 days apart — from 139 frost-free days in Larimer County to 184 in Pueblo County. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 11 counties runs 155–178 days, with a median of 169 days — a 45-day span end to end.
Measured across 11 member counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
Where the line runs inside the Front Range
The middle half of the Front Range runs 155–178 frost-free days, and 6 of its 11 counties sit outside that — 3 on the short side, 3 on the long. A regional planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 155 frost-free days
3 counties
- Larimer County · 139 days
- Boulder County · 142 days
- Jefferson County · 149 days
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
155–178 frost-free days
5 counties
0 of 5 shown
The middle half of the region, and the part a single regional season describes well.
Over 178 frost-free days
3 counties
- Pueblo County · 184 days
- Broomfield County · 184 days
- Denver County · 183 days
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its OWN 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a site within its county as well — which is the part only your address resolves.
What Grows in the Front Range
All 1 of the plants below that publish a season requirement clear even Larimer County’s 139 frost-free days — so on season alone, this grid works at both ends of the region. The 45-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the Front Range's USDA zones 5a-6a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Front Range
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Front Range’s USDA zones 5a-6a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Front Range
The USDA soil survey maps this ground county by county. These are those records weighted by land area across eleven member counties — this region’s own profile, not a state figure.
The ground is predominantly Mollisols, at 40% of mapped acres, followed by Aridisols (22%), Entisols (22%) and Alfisols (9%). Eight soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Ascalon, Olney, and Valent.
74% of those acres are well drained, and another 14% somewhat excessively drained, 6% excessively drained. Topsoil pH runs 6.0–8.2 between the lowest and the highest county on record.
Soil order
Mollisols
Drainage
Well drained
Topsoil pH
6.0–8.2
Hydric soils
2%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Larimer County holds the most wetland ground here, at 3% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Front Range
The soil survey reads this ground county by county, and the readings above are those records summed across the Front Range. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records74% of the mapped acres across the Front Range are well drained — ground that drains quickly. That is area-weighted across all eleven of its mapped counties.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
From county recordsTopsoil across the Front Range runs pH 6.0–8.2 — near neutral in nine of its eleven counties.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across the Front Range — and how to grow with it.
Across the Front Range's 11 counties the federal record holds 16,621 documented sites, mostly Underground Storage Tanks (7,521), Brownfields (4,814) and Nitrate (2,938). The heaviest single county is Denver County, with 2,786.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Front Range to see which records sit where you actually grow.
Sources Checked
Summed across the 11 counties in the Front Range
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.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Front Range
Everything above resolves to the Front Range as a whole — a footprint whose own counties record seasons 45 days apart, and hardiness across zones 5a-6a. Your parcel sits at one point in that range, not in the middle of it. 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 region 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 regional average.
Your Lot vs the Front Range Average
Front Range Average
- ●USDA Zones 5a-6a, averaged across Front Range
- ●One soil character for all of Front Range
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Front Range's 5a-6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Front Range
Pull a site-specific report for your exact address in the Front Range — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Front Range averages can't show:
We read public map data around The Front Range — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Front Range average
How we know this about the Front Range
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Front Range
What hardiness zone is the Front Range?
The Front Range spans USDA hardiness zones 5a-6a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Front Range?
Measured between 28°F hard freezes, the Front Range's counties mostly run 155 to 178 frost-free days, median 169 (NOAA Regional Climate Centers ACIS, 1991–2020, over 11 member counties). That 23-day spread is the honest read — no single season describes 11 counties, and each county guide below carries its own.
When does frost risk end in the Front Range?
Across the Front Range, the middle half of member counties see their last 28°F hard freeze between Apr 23 and May 6 (median Apr 27), and their first fall freeze between Oct 8 and Oct 17. Those are hard freezes, not the last light frost: tender transplants wait for about May 18, and elevation decides which end of a 13-day spread you garden in.
What grows well in the Front Range?
The Front Range's conditions suit plants such as Tomato, Colorado Blue Spruce, Apple, Raspberry, Hops, Chokecherry. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Front Range defined?
The Front Range is defined here as a curated cluster of 11 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Front Range cover?
The Front Range spans Colorado. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
High Plains, Colorado High Country (Central Rockies), San Luis Valley, Arkansas River Valley (Rocky Ford–Pueblo Corridor), Four Corners / Southwest Colorado, and Uncompahgre Valley share at least one state with the Front Range. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Front Range’s own scale
6 of the readings below were taken at the Front Range's own scale — the zone 5a-6a band across its footprint, a median 169-day season across its 11 counties and 16,621 documented federal contamination records across its 11 counties, 2,786 of them in Denver County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 5a-6a aggregated across all 11 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 11 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 11 counties run 155 to 178 frost-free days, median 169NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 16,621 documented federal contamination records across its 11 counties, 2,786 of them in Denver County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 40% Mollisols, topsoil pH 6.0–8.2, area-weighted across its 11 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 5a-6afrom Colorado
What this page can’t tell you
- Which end of the 23-day range your ground sits at — 155 days at one extreme, 178 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Front Range
State growing guides
Counties in this region
Other growing regions across Colorado
A semi-arid shortgrass tableland of deep soils and big sky, where wind, low rainfall, and irrigation shape dryland wheat, sorghum, and resilient gardens.
Colorado's highest gardens sit at 7,500–10,000+ feet, where frost can land in any month and the honest growing window runs 85–141 days across the region's counties — a span a single county figure hides at both ends. Because county centroids average the alpine slopes upward, the committed town data runs colder than the county page: Crested Butte gardens at zone 3b, Gunnison at 4a, Leadville sees roughly 84 frost-free days. This is the short-season opposite pole of the San Luis high-desert basin, and a completely different regime from the Front Range (169 frost-free days) or the Grand Valley (209) — season extension, cold-hardy varieties, and month-round frost vigilance drive every planting decision here.
The San Luis Valley is Colorado's high, cold intermountain basin — short frost-free seasons and hard winters — yet Rio Grande irrigation makes it one of the state's most important farming areas, famous for potatoes and barley.
Colorado's irrigated warm-season pocket. The lower Arkansas River bottomland east of the mountains runs a 178-to-191-frost-free-day season in zones 5b-6a — long and warm enough that Rocky Ford built a cantaloupe-and-watermelon reputation and Pueblo its green chile. That specialty-crop identity is nothing like the dryland shortgrass wheat and sorghum of the surrounding High Plains; what sets a parcel apart here is water. The ditch-irrigated valley floor grows heat-loving melons and chiles the unwatered tableland just above it cannot.
Southwest Colorado's Four Corners country grows on high-desert mesas at roughly 6,000-7,000 ft, where zone 6a-6b winters meet a warm-day/cool-night rhythm and a late-summer monsoon — a climate distinct from both the lower, warmer valleys of the northern Western Slope and the frost-pocket high country above it. The 146-168 frost-free days around Durango, Cortez, Mancos, and Pagosa Springs favor short-to-mid-season crops, and the Cortez-Dove Creek belt beside Mesa Verde is legendary dryland pinto-bean country (Dove Creek bills itself the "Pinto Bean Capital of the World").
The Uncompahgre River valley floor from Montrose past Olathe down to Delta, where Bureau of Reclamation irrigation and a warm 6a-to-7a valley climate stretch the frost-free season from about 130 days upvalley near Montrose to 189 days near Delta.