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

Planting zone for 66506 — Manhattan, KS

ZIP code 66506 (Manhattan, Riley County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 16 and the first fall frost October 19.

Where ZIP 66506 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 16

First frostOct 19

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Manhattan, 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 Manhattan, 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 plantsMay 1only 10% chance of frost after

First fall frostOctober 19median — 10% chance by Oct 1

Growing season185 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around October 29.

From the NOAA station Manhattan, KS — within 1 mile, elevation 1,060 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 66506

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 24 – Sep 7

GarlicPlant cloves · Oct 5 – Nov 9

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 16) and first fall frost (Oct 19) 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 66506 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 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 Manhattan, KS.

Soil in Manhattan, KS

The soil mapped at the center of ZIP 66506 is Ivan — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Ivan and Kennebec silt loams, occasionally flooded.

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 66506; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Manhattan, KS

Summer high91 °Faverage high, July

Winter low19 °Faverage low, January

Hot days59days a year at 90 °F or more

Freezing nights125nights a year at 32 °F or less

Growing degree days4,172base 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

Precipitation35.8 inper year, rain and melted snow

Snowfall18 inper year; 20 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: Manhattan, KS (within 1 mile); precipitation: Manhattan, KS (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

Saint George, KS · 9 mi

664426b

Fort Riley, KS · 13 mi

All 4 ZIP codes in Manhattan → · Kansas planting zones →

Questions about 66506

What planting zone is ZIP code 66506?

ZIP code 66506 (Manhattan, 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 Manhattan, KS?

The median last spring frost (32 °F) near 66506 is April 16; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Manhattan station.

When is the first frost in Manhattan, KS?

The median first fall frost near 66506 is October 19, giving a median frost-free growing season of 185 days.

When should I plant tomatoes in 66506?

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 66506 get?

About 35.8 inches of precipitation a year and 18 inches of snowfall (NOAA 1991–2020 normals, Manhattan station).

How hot do summers get in Manhattan, KS?

The average high peaks at 91 °F in July, with about 59 days a year at 90 °F or more.

What kind of soil does 66506 have?

The USDA soil survey maps Ivan at the center of ZIP 66506: silt loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Manhattan, KS in 2026?

Spring leaf-out near 66506 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 Manhattan, KS?

Intermediate onions: the longest day near 66506 is 14 h 56 min, so day-neutral types bulb best; long-day varieties may not bulb fully.