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

Planting zone for 81137 — Ignacio, CO

ZIP code 81137 (Ignacio, La Plata County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 23 and the first fall frost September 29.

Where ZIP 81137 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 23

First frostSep 29

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 Ignacio, 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 Ignacio, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 23median — 50% chance of a later frost

Safe for tender plantsJune 7only 10% chance of frost after

First fall frostSeptember 29median — 10% chance by Sep 18

Growing season128 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 7 and returns around October 8.

From the NOAA station Ignacio 6ese, CO — 5 miles away, elevation 6,549 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 81137

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 11 – Apr 25

SpinachSow outdoors · Apr 11 – May 2

Broccoli, cabbageStart indoors · Mar 14 – Mar 28

Broccoli, cabbageTransplant · May 2 – May 16

Onion setsPlant outdoors · Apr 25 – May 9

PotatoesPlant outdoors · May 2 – May 16

LettuceSow outdoors · Apr 25 – May 9

Carrots, beetsSow outdoors · May 2 – May 16

TomatoesStart indoors · Mar 28 – Apr 11

TomatoesTransplant · May 30 – Jun 13

Peppers, eggplantStart indoors · Mar 14 – Mar 28

Peppers, eggplantTransplant · Jun 6 – Jun 20

BeansSow outdoors · May 30 – Jun 13

Sweet cornSow outdoors · May 30 – Jun 13

Cucumbers, squashSow outdoors · May 30 – Jun 13

Fall lettuce, spinachSow outdoors · Aug 4 – Aug 18

GarlicPlant cloves · Sep 15 – Oct 20

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 23) and first fall frost (Sep 29) 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 81137 came on Mar 16 — 16 days earlier than the 1991–2020 average (Apr 1).

average
Apr 12026
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.

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 Ignacio, CO.

Soil in Ignacio, CO

The soil mapped at the center of ZIP 81137 is Tefton — loam, somewhat poorly drained.

TextureLoama good balance for most vegetables

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Tefton loam.

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 81137; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Ignacio, CO

Summer high86 °Faverage high, July

Winter low11 °Faverage low, January

Hot days21days a year at 90 °F or more

Freezing nights202nights a year at 32 °F or less

Growing degree days2,011base 50 °F — the season’s usable heat

Longest day14 h 43 mindaylight on June 21

Shortest day9 h 37 mindaylight on December 21

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

Precipitation13.5 inper year, rain and melted snow

Snowfall34 inper year; 56 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: Ignacio 6ese, CO (5 mi away); precipitation: Ignacio 6ese, CO (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

874196b

Navajo Dam, NM · 9 mi

Colorado planting zones →

Questions about 81137

What planting zone is ZIP code 81137?

ZIP code 81137 (Ignacio, 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 Ignacio, CO?

The median last spring frost (32 °F) near 81137 is May 23; after June 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ignacio 6ese station.

When is the first frost in Ignacio, CO?

The median first fall frost near 81137 is September 29, giving a median frost-free growing season of 128 days.

When should I plant tomatoes in 81137?

Start tomato seeds indoors around Mar 28 – Apr 11 and set transplants outside around May 30 – Jun 13, one to three weeks after the median last frost.

How much rain and snow does 81137 get?

About 13.5 inches of precipitation a year and 34 inches of snowfall (NOAA 1991–2020 normals, Ignacio 6ese station).

How hot do summers get in Ignacio, CO?

The average high peaks at 86 °F in July, with about 21 days a year at 90 °F or more.

What kind of soil does 81137 have?

The USDA soil survey maps Tefton at the center of ZIP 81137: loam, somewhat poorly drained, pH about 7.9 (alkaline).

Did spring come early in Ignacio, CO in 2026?

Spring leaf-out near 81137 came on Mar 16 in 2026, 16 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Ignacio, CO?

Intermediate onions: the longest day near 81137 is 14 h 43 min, so day-neutral types bulb best; long-day varieties may not bulb fully.