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

Planting zone for 80818 — Genoa, CO

ZIP code 80818 (Genoa, Lincoln County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 8 and the first fall frost October 10.

Where ZIP 80818 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 8
First frostOct 10
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 Genoa, 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 Genoa, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 8median — 50% chance of a later frost
Safe for tender plantsMay 22only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 28
Growing season155 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 28 and returns around October 20.

From the NOAA station Genoa, CO — 10 miles away, elevation 5,594 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 80818

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 27 – Apr 10
SpinachSow outdoors · Mar 27 – Apr 17
Broccoli, cabbageStart indoors · Feb 27 – Mar 13
Broccoli, cabbageTransplant · Apr 17 – May 1
Onion setsPlant outdoors · Apr 10 – Apr 24
PotatoesPlant outdoors · Apr 17 – May 1
LettuceSow outdoors · Apr 10 – Apr 24
Carrots, beetsSow outdoors · Apr 17 – May 1
TomatoesStart indoors · Mar 13 – Mar 27
TomatoesTransplant · May 15 – May 29
Peppers, eggplantStart indoors · Feb 27 – Mar 13
Peppers, eggplantTransplant · May 22 – Jun 5
BeansSow outdoors · May 15 – May 29
Sweet cornSow outdoors · May 15 – May 29
Cucumbers, squashSow outdoors · May 15 – May 29
Fall lettuce, spinachSow outdoors · Aug 15 – Aug 29
GarlicPlant cloves · Sep 26 – Oct 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 8) and first fall frost (Oct 10) 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 80818 came on Mar 1 — 29 days earlier than the 1991–2020 average (Mar 30).

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 Genoa, CO.

Soil in Genoa, CO

The soil mapped at the center of ZIP 80818 is Platner — loam, well drained.

TextureLoama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.25%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Platner-Ascalon complex, 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 80818; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Genoa, CO

Summer high86 °Faverage high, July
Winter low20 °Faverage low, February
Hot days28days a year at 90 °F or more
Freezing nights148nights a year at 32 °F or less
Growing degree days2,739base 50 °F — the season’s usable heat
Longest day14 h 57 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
Precipitation16 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 42 °F, low 21 °F 42°21° JanFebruary: average high 42 °F, low 20 °F 42°20° FebMarch: average high 52 °F, low 28 °F 52°28° MarApril: average high 59 °F, low 34 °F 59°34° AprMay: average high 69 °F, low 43 °F 69°43° MayJune: average high 80 °F, low 53 °F 80°53° JunJuly: average high 86 °F, low 59 °F 86°59° JulAugust: average high 83 °F, low 58 °F 83°58° AugSeptember: average high 76 °F, low 50 °F 76°50° SepOctober: average high 63 °F, low 38 °F 63°38° OctNovember: average high 50 °F, low 28 °F 50°28° NovDecember: average high 41 °F, low 21 °F 41°21° Dec

Precipitation by month inches

0″1″2″3″January: 0.28 in precipitation 0.3 JanFebruary: 0.32 in precipitation 0.3 FebMarch: 0.80 in precipitation 0.8 MarApril: 1.41 in precipitation 1.4 AprMay: 2.42 in precipitation 2.4 MayJune: 2.27 in precipitation 2.3 JunJuly: 2.77 in precipitation 2.8 JulAugust: 2.82 in precipitation 2.8 AugSeptember: 1.16 in precipitation 1.2 SepOctober: 1.06 in precipitation 1.1 OctNovember: 0.34 in precipitation 0.3 NovDecember: 0.38 in precipitation 0.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Genoa, CO (10 mi away); precipitation: Limon 6.9 Ne, CO (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

808045b
Arriba, CO · 13 mi
808285b
Limon, CO · 17 mi
808265b
Limon, CO · 19 mi
808155b
Flagler, CO · 20 mi
807405b
Lindon, CO · 23 mi
801015b
Agate, CO · 26 mi
807575b
Woodrow, CO · 26 mi
808015b
Anton, CO · 29 mi

Colorado planting zones →

Questions about 80818

What planting zone is ZIP code 80818?

ZIP code 80818 (Genoa, 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 Genoa, CO?

The median last spring frost (32 °F) near 80818 is May 8; after May 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Genoa station.

When is the first frost in Genoa, CO?

The median first fall frost near 80818 is October 10, giving a median frost-free growing season of 155 days.

When should I plant tomatoes in 80818?

Start tomato seeds indoors around Mar 13 – Mar 27 and set transplants outside around May 15 – May 29, one to three weeks after the median last frost.

How much rain and snow does 80818 get?

About 16 inches of precipitation a year (NOAA 1991–2020 normals, Limon 6.9 Ne station).

How hot do summers get in Genoa, CO?

The average high peaks at 86 °F in July, with about 28 days a year at 90 °F or more.

What kind of soil does 80818 have?

The USDA soil survey maps Platner at the center of ZIP 80818: loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Genoa, CO in 2026?

Spring leaf-out near 80818 came on Mar 1 in 2026, 29 days earlier than the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Genoa, CO?

Intermediate onions: the longest day near 80818 is 14 h 57 min, so day-neutral types bulb best; long-day varieties may not bulb fully.