Hartsel, Colorado, sits in USDA hardiness zone 4a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
These conditions suit zucchini, cranberry, cilantro, and okra — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Hartsel, 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 Hartsel 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 Hartsel — soil, climate, flood, and parcel records. How we handle your address.
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Hartsel — the short answer
Hartsel, Colorado: USDA zone 4a, about 89 days between hard freezes, across 128 acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jun 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~89
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 128 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 4a is Hartsel's average, not your lot's — a low corner or a tree line moves it. Against Hartsel's 89-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Hartsel
Each reading below is measured for Hartsel itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHartsel runs about 89 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredHartsel sits in USDA hardiness zone 4a.
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 Hartsel is in
Hartsel sits in the Southern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Hartsel's own centroid rather than borrowed from Park County.
What Grows in Hartsel
Every plant below cleared Hartsel's own zone 4a and its 89-day season. Each card opens that plant's Colorado profile. How we score.
Is it too late to plant in Hartsel?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around May 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jun 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 4 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Hartsel
Closest first, within ~10 miles of Hartsel. Listing isn't leaking, and distance isn't exposure.
- Antero ReservoirUnderground Storage Tanks · 1300 ft
- Badger Basin Country StoreUnderground Storage Tanks · 1300 ft
- CDOT HartselUnderground Storage Tanks · 2200 ft
- UnknownMining · 1.8 mi
- SC01207418DBC SPMW2Nitrate · 5.1 mi
- ANTERO RESERVOIRBrownfields · 5.7 mi
- SC01207416CB SPMW1Nitrate · 6.6 mi
- SC01107616CADNitrate · 6.9 mi
- Shirley May MineMining · 6.9 mi
- Garo DepositMining · 7.0 mi
- SC01107609DABNitrate · 7.5 mi
- SC01107610BCB SPMW3Nitrate · 7.5 mi
4 more sites are on the record inside the same radius. See them on the map
Measured from Hartsel'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 Hartsel.
Sources Checked
within ~10 miles of Hartsel
Severity Distribution
within ~10 miles of Hartsel
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hartsel, two things run higher than the national average within ~10 miles of Hartsel — Mining (5 sites) and Nitrate (18 sites). That's not a problem with your land — it's information about it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Hartsel
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 Hartsel average
Your land is one point inside Hartsel
Everything above resolves to Hartsel as a whole — one PHZM band and one 28°F frost record, read across 128 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 Hartsel Average
Hartsel Average
- ●USDA Zones 4a, averaged across Hartsel
- ●One soil character for all of Hartsel
- ●Frost dates read at Hartsel's scale: Jun 7 to Sep 4
YOUR Parcel
- ✓Your exact zone, not Hartsel's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Hartsel
Pull a site-specific report for your exact address in Hartsel, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hartsel averages can't show:
We read public map data around Hartsel — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hartsel average
How we know this about Hartsel
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 Hartsel’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 Hartsel
When does frost risk typically end in Hartsel?
The last hard freeze (28°F) in Hartsel typically lands around Jun 7, 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 Jun 28.
When is the first frost in Hartsel?
The first hard freeze (28°F) in Hartsel typically arrives around Sep 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Aug 21, so the watching starts about Aug 5 — about 89 days after the spring freeze cleared.
How long is the growing season in Hartsel?
Measured between 28°F hard freezes, Hartsel sees about 89 frost-free days — roughly Jun 7 through Sep 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 28 to Aug 21, about 54 days.
Is the soil safe to grow vegetables in Hartsel?
The federal record around Hartsel is a meaningful one — 27 documented sites, mostly Nitrate entries (18), the nearest Underground Storage Tanks record about 0.2 miles 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 gardeners stretch the season in Hartsel?
With about 89 frost-free days between hard freezes, Hartsel rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 117 to 145 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the Jun 7 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Hartsel's scale — its 4a band and its 89-day season. Your yard writes its own version of Hartsel'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 Hartsel’s own scale
6 of the readings below were taken at Hartsel's own scale — its own ~89-day season between 28°F freezes, the 128 acres it covers and 27 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Hartsel's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Hartsel's own 28°F hard-freeze dates, about Jun 7 and Sep 4 and the ~89-day span between themNOAA 1991–2020 Climate Normals
- 27 documented contamination sites on the federal record near Hartsel, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Hartsel's boundary and the 128 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~89-day seasonGrowable Ground crop-matching engine
- The ecoregion at Hartsel's own centroid, the Southern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Hartsel's 128 acres read through its county's SSURGO summaryfrom Park County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Park 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 Park County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Hartsel's 128 acreswhy one lot differs from the next →
- Which side of Hartsel you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 128 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Hartsel-wide figureread your own land →