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

Planting zone for 66544 — Vermillion, KS

ZIP code 66544 (Vermillion, Marshall County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 20 and the first fall frost October 18.

Where ZIP 66544 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostApr 20

First frostOct 18

2012 zone5b

Was 5b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Vermillion, KS…

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 Vermillion, KS

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 20median — 50% chance of a later frost

Safe for tender plantsMay 3only 10% chance of frost after

First fall frostOctober 18median — 10% chance by Oct 1

Growing season180 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around October 28.

From the NOAA station Frankfort 6ne, KS — 7 miles away, elevation 1,263 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 66544

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 9 – Mar 23

SpinachSow outdoors · Mar 9 – Mar 30

Broccoli, cabbageStart indoors · Feb 9 – Feb 23

Broccoli, cabbageTransplant · Mar 30 – Apr 13

Onion setsPlant outdoors · Mar 23 – Apr 6

PotatoesPlant outdoors · Mar 30 – Apr 13

LettuceSow outdoors · Mar 23 – Apr 6

Carrots, beetsSow outdoors · Mar 30 – Apr 13

TomatoesStart indoors · Feb 23 – Mar 9

TomatoesTransplant · Apr 27 – May 11

Peppers, eggplantStart indoors · Feb 9 – Feb 23

Peppers, eggplantTransplant · May 4 – May 18

BeansSow outdoors · Apr 27 – May 11

Sweet cornSow outdoors · Apr 27 – May 11

Cucumbers, squashSow outdoors · Apr 27 – May 11

Fall lettuce, spinachSow outdoors · Aug 23 – Sep 6

GarlicPlant cloves · Oct 4 – Nov 8

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 20) and first fall frost (Oct 18) 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 66544 came on Feb 25 — 26 days earlier than the 1991–2020 average (Mar 23).

average
Mar 232026
Feb 25

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 6a in Kansas

425 plants native to the lower 48 states, recorded in Kansas, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 Vermillion, KS.

Soil in Vermillion, KS

The soil mapped at the center of ZIP 66544 is Pawnee — clay loam, moderately well drained.

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

pH5.6moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter2%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classprime farmlandUSDA classification

Map unit: Pawnee clay loam, 1 to 4 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 66544; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Vermillion, KS

Summer high88 °Faverage high, July

Winter low15 °Faverage low, January

Hot days35days a year at 90 °F or more

Freezing nights142nights a year at 32 °F or less

Growing degree days3,511base 50 °F — the season’s usable heat

Longest day14 h 59 mindaylight on June 21

Shortest day9 h 21 mindaylight on December 21

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

Precipitation33.2 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: Frankfort 6ne, KS (7 mi away); precipitation: Frankfort 6ne, KS (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

Baileyville, KS · 13 mi

Kansas planting zones →

Questions about 66544

What planting zone is ZIP code 66544?

ZIP code 66544 (Vermillion, KS) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Vermillion, KS?

The median last spring frost (32 °F) near 66544 is April 20; after May 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Frankfort 6ne station.

When is the first frost in Vermillion, KS?

The median first fall frost near 66544 is October 18, giving a median frost-free growing season of 180 days.

When should I plant tomatoes in 66544?

Start tomato seeds indoors around Feb 23 – Mar 9 and set transplants outside around Apr 27 – May 11, one to three weeks after the median last frost.

How much rain and snow does 66544 get?

About 33.2 inches of precipitation a year (NOAA 1991–2020 normals, Frankfort 6ne station).

How hot do summers get in Vermillion, KS?

The average high peaks at 88 °F in July, with about 35 days a year at 90 °F or more.

What kind of soil does 66544 have?

The USDA soil survey maps Pawnee at the center of ZIP 66544: clay loam, moderately well drained, pH about 5.6 (moderately acidic).

Did spring come early in Vermillion, KS in 2026?

Spring leaf-out near 66544 came on Feb 25 in 2026, 26 days earlier than the 1991–2020 average (Mar 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Vermillion, KS?

Intermediate onions: the longest day near 66544 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 66544 change?

Yes. The 2012 USDA map put 66544 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.