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

Planting zone for 81425 — Olathe, CO

ZIP code 81425 (Olathe, Montrose County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 2 and the first fall frost October 8.

Where ZIP 81425 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostMay 2
First frostOct 8
2012 zone6b

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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Olathe, 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 Olathe, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 2median — 50% chance of a later frost
Safe for tender plantsMay 17only 10% chance of frost after
First fall frostOctober 8median — 10% chance by Sep 26
Growing season157 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 20.

From the NOAA station Montrose Regional Airport, CO — 12 miles away, elevation 5,758 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 81425

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 21 – Apr 4
SpinachSow outdoors · Mar 21 – Apr 11
Broccoli, cabbageStart indoors · Feb 21 – Mar 7
Broccoli, cabbageTransplant · Apr 11 – Apr 25
Onion setsPlant outdoors · Apr 4 – Apr 18
PotatoesPlant outdoors · Apr 11 – Apr 25
LettuceSow outdoors · Apr 4 – Apr 18
Carrots, beetsSow outdoors · Apr 11 – Apr 25
TomatoesStart indoors · Mar 7 – Mar 21
TomatoesTransplant · May 9 – May 23
Peppers, eggplantStart indoors · Feb 21 – Mar 7
Peppers, eggplantTransplant · May 16 – May 30
BeansSow outdoors · May 9 – May 23
Sweet cornSow outdoors · May 9 – May 23
Cucumbers, squashSow outdoors · May 9 – May 23
Fall lettuce, spinachSow outdoors · Aug 13 – Aug 27
GarlicPlant cloves · Sep 24 – Oct 29
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 2) and first fall frost (Oct 8) 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 81425 came on Mar 20 — 20 days earlier than the 1991–2020 average (Apr 9).

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 6b in Colorado

565 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 252

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 168

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 Olathe, CO.

Soil in Olathe, CO

The soil mapped at the center of ZIP 81425 is Moento — gravelly loam, well drained.

TextureGravelly loama good balance for most vegetables
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Moento-Beje, extremely stony complex, 10 to 35 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 81425; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Olathe, CO

Summer high90 °Faverage high, July
Winter low16 °Faverage low, January
Hot days44days a year at 90 °F or more
Freezing nights156nights a year at 32 °F or less
Growing degree days2,862base 50 °F — the season’s usable heat
Longest day14 h 51 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
Precipitation11.5 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 39 °F, low 16 °F 39°16° JanFebruary: average high 45 °F, low 22 °F 45°22° FebMarch: average high 55 °F, low 29 °F 55°29° MarApril: average high 63 °F, low 35 °F 63°35° AprMay: average high 74 °F, low 43 °F 74°43° MayJune: average high 86 °F, low 52 °F 86°52° JunJuly: average high 90 °F, low 58 °F 90°58° JulAugust: average high 87 °F, low 56 °F 87°56° AugSeptember: average high 79 °F, low 48 °F 79°48° SepOctober: average high 65 °F, low 36 °F 65°36° OctNovember: average high 51 °F, low 25 °F 51°25° NovDecember: average high 39 °F, low 16 °F 39°16° Dec

Precipitation by month inches

0″1″2″January: 0.49 in precipitation 0.5 JanFebruary: 0.50 in precipitation 0.5 FebMarch: 0.72 in precipitation 0.7 MarApril: 0.87 in precipitation 0.9 AprMay: 1.14 in precipitation 1.1 MayJune: 0.52 in precipitation 0.5 JunJuly: 1.36 in precipitation 1.4 JulAugust: 1.52 in precipitation 1.5 AugSeptember: 1.46 in precipitation 1.5 SepOctober: 1.51 in precipitation 1.5 OctNovember: 0.58 in precipitation 0.6 NovDecember: 0.84 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Montrose Regional Airport, CO (12 mi away); precipitation: Montrose 3.9 Wnw, CO (9 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.

814026b
Montrose, CO · 13 mi
814036a
Montrose, CO · 14 mi
814166b
Delta, CO · 15 mi
814016b
Montrose, CO · 19 mi
814246a
Nucla, CO · 22 mi
814146b
Cory, CO · 24 mi
814106b
Austin, CO · 25 mi
814305b
Placerville, CO · 28 mi

Colorado planting zones →

Questions about 81425

What planting zone is ZIP code 81425?

ZIP code 81425 (Olathe, CO) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Olathe, CO?

The median last spring frost (32 °F) near 81425 is May 2; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Montrose Regional Airport station.

When is the first frost in Olathe, CO?

The median first fall frost near 81425 is October 8, giving a median frost-free growing season of 157 days.

When should I plant tomatoes in 81425?

Start tomato seeds indoors around Mar 7 – Mar 21 and set transplants outside around May 9 – May 23, one to three weeks after the median last frost.

How much rain and snow does 81425 get?

About 11.5 inches of precipitation a year (NOAA 1991–2020 normals, Montrose 3.9 Wnw station).

How hot do summers get in Olathe, CO?

The average high peaks at 90 °F in July, with about 44 days a year at 90 °F or more.

What kind of soil does 81425 have?

The USDA soil survey maps Moento at the center of ZIP 81425: gravelly loam, well drained, pH about 7.2 (neutral).

Did spring come early in Olathe, CO in 2026?

Spring leaf-out near 81425 came on Mar 20 in 2026, 20 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Olathe, CO?

Intermediate onions: the longest day near 81425 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.