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

Planting zone for Parker, CO

Parker, CO is in USDA zone 5b across its 2 ZIP codes. The median last spring frost is May 9 and the first fall frost October 3.

Parker on the zone map

Outlined: its 2 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.

Zone5b−15 to −10 °F

ZIP codes2

Last frostMay 9

First frostOct 3

Growing season145 days

5b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Parker, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 9median — 50% chance of a later frost

Safe for tender plantsMay 23only 10% chance of frost after

First fall frostOctober 3median — 10% chance by Sep 21

Growing season145 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 12.

From the NOAA station Parker, CO, elevation 5,906 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 Parker

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 28 – Apr 11

SpinachSow outdoors · Mar 28 – Apr 18

Broccoli, cabbageStart indoors · Feb 28 – Mar 14

Broccoli, cabbageTransplant · Apr 18 – May 2

Onion setsPlant outdoors · Apr 11 – Apr 25

PotatoesPlant outdoors · Apr 18 – May 2

LettuceSow outdoors · Apr 11 – Apr 25

Carrots, beetsSow outdoors · Apr 18 – May 2

TomatoesStart indoors · Mar 14 – Mar 28

TomatoesTransplant · May 16 – May 30

Peppers, eggplantStart indoors · Feb 28 – Mar 14

Peppers, eggplantTransplant · May 23 – Jun 6

BeansSow outdoors · May 16 – May 30

Sweet cornSow outdoors · May 16 – May 30

Cucumbers, squashSow outdoors · May 16 – May 30

Fall lettuce, spinachSow outdoors · Aug 8 – Aug 22

GarlicPlant cloves · Sep 19 – Oct 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 9) and first fall frost (Oct 3) 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 80138 came on Feb 26 — 28 days earlier than the 1991–2020 average (Mar 26).

average
Mar 262026
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 Parker, CO.

Soil in Parker, CO

The soil mapped at the center of ZIP 80138 is Stapleton — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Stapleton-Bresser association.

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 80138; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Parker, CO

Summer high88 °Faverage high, July

Winter low14 °Faverage low, December

Hot days35days a year at 90 °F or more

Freezing nights177nights a year at 32 °F or less

Growing degree days2,541base 50 °F — the season’s usable heat

Longest day14 h 58 mindaylight on June 21

Shortest day9 h 23 mindaylight on December 21

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

Precipitation17.8 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: Parker, CO (4 mi away); precipitation: Parker 2.1 E, CO (3 mi away). Daylight is calculated from latitude.

ZIP codes in Parker

Colorado planting zones →

Questions about Parker

What planting zone is Parker, CO?

Parker, CO is in USDA hardiness zone 5b on the 2023 map (5b: −15 to −10 °F).

When is the last frost in Parker, CO?

The median last spring frost is May 9 and the median first fall frost is October 3 (NOAA 1991–2020 normals, Parker station).

When can I plant a garden in Parker, CO?

Cool-season crops like peas and spinach go in around Mar 28 – Apr 18; tomatoes, peppers, beans and squash after about May 16, once frost risk has passed.

What kind of onions grow in Parker, 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 Parker, CO get?

About 17.8 inches of precipitation a year (NOAA 1991–2020 normals).