Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 81043 — Hartman, CO

ZIP code 81043 (Hartman, Prowers County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 1 and the first fall frost October 12.

Where ZIP 81043 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostMay 1
First frostOct 12
2012 zone6a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Hartman, CO…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Hartman, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 1median — 50% chance of a later frost
Safe for tender plantsMay 14only 10% chance of frost after
First fall frostOctober 12median — 10% chance by Sep 29
Growing season163 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 21 and returns around October 21.

From the NOAA station Holly, CO — 7 miles away, elevation 3,402 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 81043

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 20 – Apr 3
SpinachSow outdoors · Mar 20 – Apr 10
Broccoli, cabbageStart indoors · Feb 20 – Mar 6
Broccoli, cabbageTransplant · Apr 10 – Apr 24
Onion setsPlant outdoors · Apr 3 – Apr 17
PotatoesPlant outdoors · Apr 10 – Apr 24
LettuceSow outdoors · Apr 3 – Apr 17
Carrots, beetsSow outdoors · Apr 10 – Apr 24
TomatoesStart indoors · Mar 6 – Mar 20
TomatoesTransplant · May 8 – May 22
Peppers, eggplantStart indoors · Feb 20 – Mar 6
Peppers, eggplantTransplant · May 15 – May 29
BeansSow outdoors · May 8 – May 22
Sweet cornSow outdoors · May 8 – May 22
Cucumbers, squashSow outdoors · May 8 – May 22
Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31
GarlicPlant cloves · Sep 28 – Nov 2
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 12) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 81043 came on Feb 26 — 18 days earlier than the 1991–2020 average (Mar 16).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 6a in Colorado

563 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 28

American elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack walnut100 ft · blooms late spring · high shade tolerance · to −28 °Fblack willow100 ft · blooms early spring · high shade tolerance · to −58 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °F

Shrubs 104

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FApache plume6 ft · blooms late spring · high shade tolerance · to −23 °F

Wildflowers & perennials 251

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine aster0.3 ft · blooms early summer · medium shade tolerance · to −28 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °F

Grasses 167

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 4

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Hartman, CO.

Soil in Hartman, CO

The soil mapped at the center of ZIP 81043 is Colby — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Colby silt loam, 0 to 3 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 81043; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hartman, CO

Summer high93 °Faverage high, July
Winter low15 °Faverage low, January
Hot days73days a year at 90 °F or more
Freezing nights161nights a year at 32 °F or less
Growing degree days3,636base 50 °F — the season’s usable heat
Longest day14 h 49 mindaylight on June 21
Shortest day9 h 31 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation17.3 inper year, rain and melted snow
Snowfall22 inper year; 18 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 46 °F, low 15 °F 46°15° JanFebruary: average high 50 °F, low 18 °F 50°18° FebMarch: average high 60 °F, low 26 °F 60°26° MarApril: average high 68 °F, low 34 °F 68°34° AprMay: average high 78 °F, low 46 °F 78°46° MayJune: average high 89 °F, low 56 °F 89°56° JunJuly: average high 93 °F, low 63 °F 93°63° JulAugust: average high 91 °F, low 61 °F 91°61° AugSeptember: average high 83 °F, low 51 °F 83°51° SepOctober: average high 71 °F, low 37 °F 71°37° OctNovember: average high 57 °F, low 24 °F 57°24° NovDecember: average high 46 °F, low 15 °F 46°15° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.39 in precipitation, 4.2 in snowfall 0.4❄4 JanFebruary: 0.34 in precipitation, 3.4 in snowfall 0.3❄3 FebMarch: 0.88 in precipitation, 4.7 in snowfall 0.9❄5 MarApril: 1.45 in precipitation, 1.4 in snowfall 1.4❄1 AprMay: 2.16 in precipitation, 0.7 in snowfall 2.2❄1 MayJune: 2.51 in precipitation 2.5 JunJuly: 2.99 in precipitation 3.0 JulAugust: 2.89 in precipitation 2.9 AugSeptember: 1.18 in precipitation 1.2 SepOctober: 1.33 in precipitation, 1 in snowfall 1.3❄1 OctNovember: 0.61 in precipitation, 3.2 in snowfall 0.6❄3 NovDecember: 0.52 in precipitation, 2.9 in snowfall 0.5❄3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Holly, CO (7 mi away); precipitation: Holly, CO (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

810476a
Holly, CO · 8 mi
678366a
Coolidge, KS · 14 mi
810416a
Granada, CO · 21 mi
810716a
Sheridan Lake, CO · 22 mi
678786a
Syracuse, KS · 24 mi
810526a
Lamar, CO · 25 mi
678796a
Tribune, KS · 34 mi
678576a
Kendall, KS · 38 mi

Colorado planting zones →

Questions about 81043

What planting zone is ZIP code 81043?

ZIP code 81043 (Hartman, CO) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Hartman, CO?

The median last spring frost (32 °F) near 81043 is May 1; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Holly station.

When is the first frost in Hartman, CO?

The median first fall frost near 81043 is October 12, giving a median frost-free growing season of 163 days.

When should I plant tomatoes in 81043?

Start tomato seeds indoors around Mar 6 – Mar 20 and set transplants outside around May 8 – May 22, one to three weeks after the median last frost.

How much rain and snow does 81043 get?

About 17.3 inches of precipitation a year and 22 inches of snowfall (NOAA 1991–2020 normals, Holly station).

How hot do summers get in Hartman, CO?

The average high peaks at 93 °F in July, with about 73 days a year at 90 °F or more.

What kind of soil does 81043 have?

The USDA soil survey maps Colby at the center of ZIP 81043: silt loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Hartman, CO in 2026?

Spring leaf-out near 81043 came on Feb 26 in 2026, 18 days earlier than the 1991–2020 average (Mar 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hartman, CO?

Intermediate onions: the longest day near 81043 is 14 h 49 min, so day-neutral types bulb best; long-day varieties may not bulb fully.