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

Planting zone for 66401 — Alma, KS

ZIP code 66401 (Alma, Wabaunsee County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 16 and the first fall frost October 23.

Where ZIP 66401 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostApr 16

First frostOct 23

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Alma, 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 Alma, KS

JanFebMarAprMayJunJulAugSepOctNovDec

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

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

Safe for tender plantsApril 30only 10% chance of frost after

First fall frostOctober 23median — 10% chance by Oct 9

Growing season189 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around November 1.

From the NOAA station Eskridge, KS — 12 miles away, elevation 1,411 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 66401

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 5 – Mar 19

SpinachSow outdoors · Mar 5 – Mar 26

Broccoli, cabbageStart indoors · Feb 5 – Feb 19

Broccoli, cabbageTransplant · Mar 26 – Apr 9

Onion setsPlant outdoors · Mar 19 – Apr 2

PotatoesPlant outdoors · Mar 26 – Apr 9

LettuceSow outdoors · Mar 19 – Apr 2

Carrots, beetsSow outdoors · Mar 26 – Apr 9

TomatoesStart indoors · Feb 19 – Mar 5

TomatoesTransplant · Apr 23 – May 7

Peppers, eggplantStart indoors · Feb 5 – Feb 19

Peppers, eggplantTransplant · Apr 30 – May 14

BeansSow outdoors · Apr 23 – May 7

Sweet cornSow outdoors · Apr 23 – May 7

Cucumbers, squashSow outdoors · Apr 23 – May 7

Fall lettuce, spinachSow outdoors · Aug 28 – Sep 11

GarlicPlant cloves · Oct 9 – Nov 13

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 16) and first fall frost (Oct 23) 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 66401 came on Feb 25 — 22 days earlier than the 1991–2020 average (Mar 19).

average
Mar 192026
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 6b in Kansas

431 plants native to the lower 48 states, recorded in Kansas, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Alma, KS.

Soil in Alma, KS

The soil mapped at the center of ZIP 66401 is Florence — gravelly silt loam, well drained.

TextureGravelly silt loama good balance for most vegetables

pH6.0slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Florence-Labette complex, 2 to 12 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 66401; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Alma, KS

Summer high89 °Faverage high, July

Winter low18 °Faverage low, January

Hot days33days a year at 90 °F or more

Freezing nights122nights a year at 32 °F or less

Growing degree days3,844base 50 °F — the season’s usable heat

Longest day14 h 54 mindaylight on June 21

Shortest day9 h 26 mindaylight on December 21

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

Precipitation35.8 inper year, rain and melted snow

Snowfall17 inper year; 21 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Eskridge, KS (12 mi away); precipitation: Mc Farland, KS (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

665016b

Mc Farland, KS · 9 mi

668346b

Alta Vista, KS · 9 mi

Maple Hill, KS · 17 mi

668336b

Allen, KS · 17 mi

665026a

Manhattan, KS · 19 mi

Kansas planting zones →

Questions about 66401

What planting zone is ZIP code 66401?

ZIP code 66401 (Alma, KS) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Alma, KS?

The median last spring frost (32 °F) near 66401 is April 16; after April 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Eskridge station.

When is the first frost in Alma, KS?

The median first fall frost near 66401 is October 23, giving a median frost-free growing season of 189 days.

When should I plant tomatoes in 66401?

Start tomato seeds indoors around Feb 19 – Mar 5 and set transplants outside around Apr 23 – May 7, one to three weeks after the median last frost.

How much rain and snow does 66401 get?

About 35.8 inches of precipitation a year and 17 inches of snowfall (NOAA 1991–2020 normals, Mc Farland station).

How hot do summers get in Alma, KS?

The average high peaks at 89 °F in July, with about 33 days a year at 90 °F or more.

What kind of soil does 66401 have?

The USDA soil survey maps Florence at the center of ZIP 66401: gravelly silt loam, well drained, pH about 6.0 (slightly acidic).

Did spring come early in Alma, KS in 2026?

Spring leaf-out near 66401 came on Feb 25 in 2026, 22 days earlier than the 1991–2020 average (Mar 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Alma, KS?

Intermediate onions: the longest day near 66401 is 14 h 54 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 66401 change?

Yes. The 2012 USDA map put 66401 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.