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

Planting zone for Littleton, CO

Littleton, CO is in USDA zones 5b to 6a across its 16 ZIP codes. The median last spring frost is May 2 and the first fall frost October 11.

Littleton on the zone map

Outlined: its 10 ZIP code areas · 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.

Zones5b–6a−15 to −5 °F
ZIP codes16
Last frostMay 2
First frostOct 11
Growing season160 days

5b 2 ZIPs   6a 14 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Littleton, 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 Littleton, 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 11median — 10% chance by Sep 27
Growing season160 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 21.

From the NOAA station Marston Fltr Plt, CO, elevation 5,611 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 Littleton

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 16 – Aug 30
GarlicPlant cloves · Sep 27 – Nov 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 2) and first fall frost (Oct 11) 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 80129 came on Feb 23 — 26 days earlier than the 1991–2020 average (Mar 21).

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.

Trees 27

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 98

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 246

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 163

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 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °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 Littleton, CO.

Soil in Littleton, CO

The soil mapped at the center of ZIP 80129 is Blakeland — loamy sand, somewhat excessively drained.

TextureLoamy sanddrains and warms fast; dries out and needs more feeding
pH7.0neutral; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter3%moderate
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Blakeland loamy sand, 9 to 15 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 80129; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Littleton, CO

Summer high86 °Faverage high, July
Winter low19 °Faverage low, January
Hot days33days a year at 90 °F or more
Freezing nights147nights a year at 32 °F or less
Growing degree days2,772base 50 °F — the season’s usable heat
Longest day14 h 58 mindaylight on June 21
Shortest day9 h 22 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation18.2 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 46 °F, low 19 °F 46°19° JanFebruary: average high 47 °F, low 20 °F 47°20° FebMarch: average high 55 °F, low 28 °F 55°28° MarApril: average high 60 °F, low 35 °F 60°35° AprMay: average high 69 °F, low 44 °F 69°44° MayJune: average high 81 °F, low 53 °F 81°53° JunJuly: average high 86 °F, low 60 °F 86°60° JulAugust: average high 85 °F, low 58 °F 85°58° AugSeptember: average high 77 °F, low 49 °F 77°49° SepOctober: average high 64 °F, low 37 °F 64°37° OctNovember: average high 53 °F, low 28 °F 53°28° NovDecember: average high 45 °F, low 20 °F 45°20° Dec

Precipitation by month inches

0″1″2″3″January: 0.62 in precipitation 0.6 JanFebruary: 0.80 in precipitation 0.8 FebMarch: 1.47 in precipitation 1.5 MarApril: 2.37 in precipitation 2.4 AprMay: 2.33 in precipitation 2.3 MayJune: 1.96 in precipitation 2.0 JunJuly: 2.08 in precipitation 2.1 JulAugust: 2.22 in precipitation 2.2 AugSeptember: 1.44 in precipitation 1.4 SepOctober: 1.36 in precipitation 1.4 OctNovember: 0.91 in precipitation 0.9 NovDecember: 0.62 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Marston Fltr Plt, CO (6 mi away); precipitation: Highlands Ranch 0.6 Sse, CO (2 mi away). Daylight is calculated from latitude.

ZIP codes in Littleton

801206a
−10 to −5 °F
801216a
−10 to −5 °F
801226a
−10 to −5 °F
801236a
−10 to −5 °F
801255b
−15 to −10 °F
801266a
−10 to −5 °F
801275b
−15 to −10 °F
801286a
−10 to −5 °F
801296a
−10 to −5 °F
801306a
−10 to −5 °F
801606a
−10 to −5 °F
801616a
−10 to −5 °F
801626a
−10 to −5 °F
801636a
−10 to −5 °F
801656a
−10 to −5 °F
801666a
−10 to −5 °F

Colorado planting zones →

Questions about Littleton

What planting zone is Littleton, CO?

Littleton, CO is in USDA hardiness zones 5b to 6a on the 2023 map (5b: −15 to −10 °F; 6a: −10 to −5 °F).

When is the last frost in Littleton, CO?

The median last spring frost is May 2 and the median first fall frost is October 11 (NOAA 1991–2020 normals, Marston Fltr Plt station).

When can I plant a garden in Littleton, CO?

Cool-season crops like peas and spinach go in around Mar 21 – Apr 11; tomatoes, peppers, beans and squash after about May 9, once frost risk has passed.

What kind of onions grow in Littleton, CO?

Intermediate onions: the longest day is 14 h 58 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Littleton, CO get?

About 18.2 inches of precipitation a year (NOAA 1991–2020 normals).