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

Planting zone for 80116 — Franktown, CO

ZIP code 80116 (Franktown, Douglas County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 16 and the first fall frost October 2.

Where ZIP 80116 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostMay 16

First frostOct 2

2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Franktown, 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 Franktown, CO

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 16median — 50% chance of a later frost

Safe for tender plantsJune 1only 10% chance of frost after

First fall frostOctober 2median — 10% chance by Sep 18

Growing season137 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 6 and returns around October 10.

From the NOAA station Elizabeth 2nw, CO — 6 miles away, elevation 6,611 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 80116

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 4 – Apr 18

SpinachSow outdoors · Apr 4 – Apr 25

Broccoli, cabbageStart indoors · Mar 7 – Mar 21

Broccoli, cabbageTransplant · Apr 25 – May 9

Onion setsPlant outdoors · Apr 18 – May 2

PotatoesPlant outdoors · Apr 25 – May 9

LettuceSow outdoors · Apr 18 – May 2

Carrots, beetsSow outdoors · Apr 25 – May 9

TomatoesStart indoors · Mar 21 – Apr 4

TomatoesTransplant · May 23 – Jun 6

Peppers, eggplantStart indoors · Mar 7 – Mar 21

Peppers, eggplantTransplant · May 30 – Jun 13

BeansSow outdoors · May 23 – Jun 6

Sweet cornSow outdoors · May 23 – Jun 6

Cucumbers, squashSow outdoors · May 23 – Jun 6

Fall lettuce, spinachSow outdoors · Aug 7 – Aug 21

GarlicPlant cloves · Sep 18 – Oct 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Oct 2) 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 80116 came on Mar 1 — 30 days earlier than the 1991–2020 average (Mar 31).

average
Mar 312026
Mar 1

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 Franktown, CO.

Soil in Franktown, CO

The soil mapped at the center of ZIP 80116 is Fondis — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Fondis clay loam, 3 to 9 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 80116; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Franktown, CO

Summer high85 °Faverage high, July

Winter low17 °Faverage low, December

Hot days19days a year at 90 °F or more

Freezing nights170nights a year at 32 °F or less

Growing degree days2,321base 50 °F — the season’s usable heat

Longest day14 h 56 mindaylight on June 21

Shortest day9 h 24 mindaylight on December 21

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

Precipitation18.5 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: Elizabeth 2nw, CO (6 mi away); precipitation: Franktown 2.1 Ene, CO (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

801045b

Castle Rock, CO · 6 mi

801075b

Elizabeth, CO · 10 mi

801095b

Castle Rock, CO · 11 mi

801085b

Castle Rock, CO · 12 mi

Colorado planting zones →

Questions about 80116

What planting zone is ZIP code 80116?

ZIP code 80116 (Franktown, CO) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Franktown, CO?

The median last spring frost (32 °F) near 80116 is May 16; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Elizabeth 2nw station.

When is the first frost in Franktown, CO?

The median first fall frost near 80116 is October 2, giving a median frost-free growing season of 137 days.

When should I plant tomatoes in 80116?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 80116 get?

About 18.5 inches of precipitation a year (NOAA 1991–2020 normals, Franktown 2.1 Ene station).

How hot do summers get in Franktown, CO?

The average high peaks at 85 °F in July, with about 19 days a year at 90 °F or more.

What kind of soil does 80116 have?

The USDA soil survey maps Fondis at the center of ZIP 80116: clay loam, well drained, pH about 7.2 (neutral).

Did spring come early in Franktown, CO in 2026?

Spring leaf-out near 80116 came on Mar 1 in 2026, 30 days earlier than the 1991–2020 average (Mar 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Franktown, CO?

Intermediate onions: the longest day near 80116 is 14 h 56 min, so day-neutral types bulb best; long-day varieties may not bulb fully.