Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 81045 — Haswell, CO

ZIP code 81045 (Haswell, Kiowa County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 30 and the first fall frost October 13.

Where ZIP 81045 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostApr 30

First frostOct 13

2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Haswell, 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 Haswell, CO

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 30median — 50% chance of a later frost

Safe for tender plantsMay 12only 10% chance of frost after

First fall frostOctober 13median — 10% chance by Oct 1

Growing season165 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 21.

From the NOAA station Eads, CO — 21 miles away, elevation 4,213 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 81045

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 19 – Apr 2

SpinachSow outdoors · Mar 19 – Apr 9

Broccoli, cabbageStart indoors · Feb 19 – Mar 5

Broccoli, cabbageTransplant · Apr 9 – Apr 23

Onion setsPlant outdoors · Apr 2 – Apr 16

PotatoesPlant outdoors · Apr 9 – Apr 23

LettuceSow outdoors · Apr 2 – Apr 16

Carrots, beetsSow outdoors · Apr 9 – Apr 23

TomatoesStart indoors · Mar 5 – Mar 19

TomatoesTransplant · May 7 – May 21

Peppers, eggplantStart indoors · Feb 19 – Mar 5

Peppers, eggplantTransplant · May 14 – May 28

BeansSow outdoors · May 7 – May 21

Sweet cornSow outdoors · May 7 – May 21

Cucumbers, squashSow outdoors · May 7 – May 21

Fall lettuce, spinachSow outdoors · Aug 18 – Sep 1

GarlicPlant cloves · Sep 29 – Nov 3

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 13) 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 81045 came on Mar 2 — 19 days earlier than the 1991–2020 average (Mar 21).

average
Mar 212026
Mar 2

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 5b in Colorado

546 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

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 Haswell, CO.

Soil in Haswell, CO

The soil mapped at the center of ZIP 81045 is Baca — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up

pH7.5slightly alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Baca-Wiley complex, 0 to 2 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 81045; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Haswell, CO

Summer high91 °Faverage high, July

Winter low16 °Faverage low, January

Hot days60days a year at 90 °F or more

Freezing nights156nights a year at 32 °F or less

Growing degree days3,415base 50 °F — the season’s usable heat

Longest day14 h 52 mindaylight on June 21

Shortest day9 h 28 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation14.5 inper year, rain and melted snow

Snowfall27 inper year; 18 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Eads, CO (21 mi away); precipitation: Haswell, CO (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

810215b

Arlington, CO · 16 mi

Wild Horse, CO · 25 mi

808255b

Kit Carson, CO · 26 mi

810926a

Wiley, CO · 28 mi

810765b

Sugar City, CO · 29 mi

810576a

Mc Clave, CO · 33 mi

Colorado planting zones →

Questions about 81045

What planting zone is ZIP code 81045?

ZIP code 81045 (Haswell, CO) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Haswell, CO?

The median last spring frost (32 °F) near 81045 is April 30; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Eads station.

When is the first frost in Haswell, CO?

The median first fall frost near 81045 is October 13, giving a median frost-free growing season of 165 days.

When should I plant tomatoes in 81045?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 81045 get?

About 14.5 inches of precipitation a year and 27 inches of snowfall (NOAA 1991–2020 normals, Haswell station).

How hot do summers get in Haswell, CO?

The average high peaks at 91 °F in July, with about 60 days a year at 90 °F or more.

What kind of soil does 81045 have?

The USDA soil survey maps Baca at the center of ZIP 81045: clay loam, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Haswell, CO in 2026?

Spring leaf-out near 81045 came on Mar 2 in 2026, 19 days earlier than the 1991–2020 average (Mar 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Haswell, CO?

Intermediate onions: the longest day near 81045 is 14 h 52 min, so day-neutral types bulb best; long-day varieties may not bulb fully.