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

Planting zone for Brighton, CO

Brighton, CO is in USDA zones 5b to 6a across its 3 ZIP codes. The median last spring frost is May 3 and the first fall frost October 7.

Brighton on the zone map

Outlined: its 3 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 codes3

Last frostMay 3

First frostOct 7

Growing season155 days

5b 2 ZIPs 6a 1 ZIP

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Brighton, 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 Brighton, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 3median — 50% chance of a later frost

Safe for tender plantsMay 16only 10% chance of frost after

First fall frostOctober 7median — 10% chance by Sep 26

Growing season155 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 16.

From the NOAA station Brighton 3 Se, CO, elevation 5,017 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 Brighton

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 22 – Apr 5

SpinachSow outdoors · Mar 22 – Apr 12

Broccoli, cabbageStart indoors · Feb 22 – Mar 8

Broccoli, cabbageTransplant · Apr 12 – Apr 26

Onion setsPlant outdoors · Apr 5 – Apr 19

PotatoesPlant outdoors · Apr 12 – Apr 26

LettuceSow outdoors · Apr 5 – Apr 19

Carrots, beetsSow outdoors · Apr 12 – Apr 26

TomatoesStart indoors · Mar 8 – Mar 22

TomatoesTransplant · May 10 – May 24

Peppers, eggplantStart indoors · Feb 22 – Mar 8

Peppers, eggplantTransplant · May 17 – May 31

BeansSow outdoors · May 10 – May 24

Sweet cornSow outdoors · May 10 – May 24

Cucumbers, squashSow outdoors · May 10 – May 24

Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26

GarlicPlant cloves · Sep 23 – Oct 28

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 7) 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 80601 came on Feb 26 — 23 days earlier than the 1991–2020 average (Mar 21).

average
Mar 212026
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 Brighton, CO.

Soil in Brighton, CO

The soil mapped at the center of ZIP 80601 is Ascalon — loamy sand, well drained.

TextureLoamy sanddrains and warms fast; dries out and needs more feeding

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Ascalon loamy sand, 0 to 3 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 80601; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Brighton, CO

Summer high90 °Faverage high, July

Winter low16 °Faverage low, January

Hot days49days a year at 90 °F or more

Freezing nights163nights a year at 32 °F or less

Growing degree days2,923base 50 °F — the season’s usable heat

Longest day15 h 01 mindaylight on June 21

Shortest day9 h 20 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation14.4 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: Brighton 3 Se, CO (2 mi away); precipitation: Brighton 1.7 Ese, CO (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Brighton

Colorado planting zones →

Questions about Brighton

What planting zone is Brighton, CO?

Brighton, 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 Brighton, CO?

The median last spring frost is May 3 and the median first fall frost is October 7 (NOAA 1991–2020 normals, Brighton 3 Se station).

When can I plant a garden in Brighton, CO?

Cool-season crops like peas and spinach go in around Mar 22 – Apr 12; tomatoes, peppers, beans and squash after about May 10, once frost risk has passed.

What kind of onions grow in Brighton, CO?

Long-day onions: the longest day is 15 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Brighton, CO get?

About 14.4 inches of precipitation a year (NOAA 1991–2020 normals).