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

Planting zone for 81223 — Cotopaxi, CO

ZIP code 81223 (Cotopaxi, Fremont County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is June 11 and the first fall frost September 9.

Where ZIP 81223 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 frostJun 11

First frostSep 9

2012 zone5a

Was 5a on the 2012 map — half a zone warmer now. 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 Cotopaxi, 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 Cotopaxi, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 11median — 50% chance of a later frost

Safe for tender plantsJune 28only 10% chance of frost after

First fall frostSeptember 9median — 10% chance by Aug 28

Growing season89 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 28 and returns around September 20.

From the NOAA station Westcliffe, CO — 18 miles away, elevation 7,874 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 81223

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 30 – May 14

SpinachSow outdoors · Apr 30 – May 21

Broccoli, cabbageStart indoors · Apr 2 – Apr 16

Broccoli, cabbageTransplant · May 21 – Jun 4

Onion setsPlant outdoors · May 14 – May 28

PotatoesPlant outdoors · May 21 – Jun 4

LettuceSow outdoors · May 14 – May 28

Carrots, beetsSow outdoors · May 21 – Jun 4

TomatoesStart indoors · Apr 16 – Apr 30

TomatoesTransplant · Jun 18 – Jul 2

Peppers, eggplantStart indoors · Apr 2 – Apr 16

Peppers, eggplantTransplant · Jun 25 – Jul 9

BeansSow outdoors · Jun 18 – Jul 2

Sweet cornSow outdoors · Jun 18 – Jul 2

Cucumbers, squashSow outdoors · Jun 18 – Jul 2

Fall lettuce, spinachSow outdoors · Jul 15 – Jul 29

GarlicPlant cloves · Aug 26 – Sep 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 11) and first fall frost (Sep 9) 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 81223 came on Feb 26 — 31 days earlier than the 1991–2020 average (Mar 29).

average
Mar 292026
Feb 26

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 Cotopaxi, CO.

Soil in Cotopaxi, CO

The soil mapped at the center of ZIP 81223 is Coaldale — very gravelly sandy loam, well drained.

TextureVery gravelly sandy loamdrains and warms fast; dries out and needs more feeding

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Coaldale very gravelly sandy loam, 20 to 45 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 81223; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cotopaxi, CO

Summer high81 °Faverage high, July

Winter low8 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights213nights a year at 32 °F or less

Growing degree days1,279base 50 °F — the season’s usable heat

Longest day14 h 50 mindaylight on June 21

Shortest day9 h 29 mindaylight on December 21

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

Precipitation15.9 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Westcliffe, CO (18 mi away); precipitation: Cotopaxi 4.8 Sse, CO (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

812325b

Hillside, CO · 6 mi

812156a

Canon City, CO · 11 mi

Canon City, CO · 16 mi

811435b

Moffat, CO · 19 mi

812525b

Westcliffe, CO · 20 mi

812446a

Rockvale, CO · 24 mi

Colorado planting zones →

Questions about 81223

What planting zone is ZIP code 81223?

ZIP code 81223 (Cotopaxi, 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 Cotopaxi, CO?

The median last spring frost (32 °F) near 81223 is June 11; after June 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Westcliffe station.

When is the first frost in Cotopaxi, CO?

The median first fall frost near 81223 is September 9, giving a median frost-free growing season of 89 days.

When should I plant tomatoes in 81223?

Start tomato seeds indoors around Apr 16 – Apr 30 and set transplants outside around Jun 18 – Jul 2, one to three weeks after the median last frost.

How much rain and snow does 81223 get?

About 15.9 inches of precipitation a year (NOAA 1991–2020 normals, Cotopaxi 4.8 Sse station).

How hot do summers get in Cotopaxi, CO?

The average high peaks at 81 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 81223 have?

The USDA soil survey maps Coaldale at the center of ZIP 81223: very gravelly sandy loam, well drained, pH about 7.0 (neutral).

Did spring come early in Cotopaxi, CO in 2026?

Spring leaf-out near 81223 came on Feb 26 in 2026, 31 days earlier than the 1991–2020 average (Mar 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cotopaxi, CO?

Intermediate onions: the longest day near 81223 is 14 h 50 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 81223 change?

Yes. The 2012 USDA map put 81223 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.