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

Planting zone for 81403 — Montrose, CO

ZIP code 81403 (Montrose, Montrose County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 28 and the first fall frost October 14.

Where ZIP 81403 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 frostApr 28
First frostOct 14
2012 zone6b

Was 6b on the 2012 map — half a zone colder now. 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 Montrose, 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 Montrose, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 28median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 14median — 10% chance by Oct 1
Growing season167 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 14 and returns around October 24.

From the NOAA station Montrose #2, CO — 12 miles away, elevation 5,791 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 81403

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 17 – Mar 31
SpinachSow outdoors · Mar 17 – Apr 7
Broccoli, cabbageStart indoors · Feb 17 – Mar 3
Broccoli, cabbageTransplant · Apr 7 – Apr 21
Onion setsPlant outdoors · Mar 31 – Apr 14
PotatoesPlant outdoors · Apr 7 – Apr 21
LettuceSow outdoors · Mar 31 – Apr 14
Carrots, beetsSow outdoors · Apr 7 – Apr 21
TomatoesStart indoors · Mar 3 – Mar 17
TomatoesTransplant · May 5 – May 19
Peppers, eggplantStart indoors · Feb 17 – Mar 3
Peppers, eggplantTransplant · May 12 – May 26
BeansSow outdoors · May 5 – May 19
Sweet cornSow outdoors · May 5 – May 19
Cucumbers, squashSow outdoors · May 5 – May 19
Fall lettuce, spinachSow outdoors · Aug 19 – Sep 2
GarlicPlant cloves · Sep 30 – Nov 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 14) 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 81403 came on Mar 20 — 21 days earlier than the 1991–2020 average (Apr 10).

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 Montrose, CO.

Soil in Montrose, CO

The soil mapped at the center of ZIP 81403 is Arabrab — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH4.5strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter75%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Arabrab-Evpark-Parkelei complex, 3 to 20 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 81403; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Montrose, CO

Summer high90 °Faverage high, July
Winter low18 °Faverage low, January
Hot days35days a year at 90 °F or more
Freezing nights155nights a year at 32 °F or less
Growing degree days3,044base 50 °F — the season’s usable heat
Longest day14 h 50 mindaylight on June 21
Shortest day9 h 30 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation10.4 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 40 °F, low 18 °F 40°18° JanFebruary: average high 46 °F, low 23 °F 46°23° FebMarch: average high 57 °F, low 30 °F 57°30° MarApril: average high 64 °F, low 37 °F 64°37° AprMay: average high 74 °F, low 45 °F 74°45° MayJune: average high 86 °F, low 53 °F 86°53° JunJuly: average high 90 °F, low 59 °F 90°59° JulAugust: average high 87 °F, low 58 °F 87°58° AugSeptember: average high 79 °F, low 49 °F 79°49° SepOctober: average high 67 °F, low 37 °F 67°37° OctNovember: average high 52 °F, low 27 °F 52°27° NovDecember: average high 41 °F, low 18 °F 41°18° Dec

Precipitation by month inches

0″1″2″January: 0.65 in precipitation 0.7 JanFebruary: 0.63 in precipitation 0.6 FebMarch: 0.69 in precipitation 0.7 MarApril: 0.90 in precipitation 0.9 AprMay: 0.84 in precipitation 0.8 MayJune: 0.61 in precipitation 0.6 JunJuly: 1.24 in precipitation 1.2 JulAugust: 1.20 in precipitation 1.2 AugSeptember: 1.12 in precipitation 1.1 SepOctober: 1.09 in precipitation 1.1 OctNovember: 0.70 in precipitation 0.7 NovDecember: 0.77 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Montrose #2, CO (12 mi away); precipitation: Montrose 1.2 Wsw, CO (11 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.

814026b
Montrose, CO · 12 mi
814256b
Olathe, CO · 14 mi
814326a
Ridgway, CO · 16 mi
814016b
Montrose, CO · 16 mi
814305b
Placerville, CO · 20 mi
812205b
Cimarron, CO · 24 mi
814275b
Ouray, CO · 26 mi
814156a
Crawford, CO · 27 mi

All 3 ZIP codes in Montrose → · Colorado planting zones →

Questions about 81403

What planting zone is ZIP code 81403?

ZIP code 81403 (Montrose, 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 Montrose, CO?

The median last spring frost (32 °F) near 81403 is April 28; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Montrose #2 station.

When is the first frost in Montrose, CO?

The median first fall frost near 81403 is October 14, giving a median frost-free growing season of 167 days.

When should I plant tomatoes in 81403?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 81403 get?

About 10.4 inches of precipitation a year (NOAA 1991–2020 normals, Montrose 1.2 Wsw station).

How hot do summers get in Montrose, CO?

The average high peaks at 90 °F in July, with about 35 days a year at 90 °F or more.

What kind of soil does 81403 have?

The USDA soil survey maps Arabrab at the center of ZIP 81403: slightly decomposed plant material, well drained, pH about 4.5 (strongly acidic).

Did spring come early in Montrose, CO in 2026?

Spring leaf-out near 81403 came on Mar 20 in 2026, 21 days earlier than the 1991–2020 average (Apr 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Montrose, CO?

Intermediate onions: the longest day near 81403 is 14 h 50 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 81403 change?

Yes. The 2012 USDA map put 81403 in zone 6b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.