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

Planting zone for 67738 — Grinnell, KS

ZIP code 67738 (Grinnell, Gove County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 6 and the first fall frost October 9.

Where ZIP 67738 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 frostMay 6

First frostOct 9

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 Grinnell, 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 Grinnell, KS

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 6median — 50% chance of a later frost

Safe for tender plantsMay 18only 10% chance of frost after

First fall frostOctober 9median — 10% chance by Sep 27

Growing season156 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 18.

From the NOAA station Oakley 4w, KS — 17 miles away, elevation 3,104 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 67738

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 25 – Apr 8

SpinachSow outdoors · Mar 25 – Apr 15

Broccoli, cabbageStart indoors · Feb 25 – Mar 11

Broccoli, cabbageTransplant · Apr 15 – Apr 29

Onion setsPlant outdoors · Apr 8 – Apr 22

PotatoesPlant outdoors · Apr 15 – Apr 29

LettuceSow outdoors · Apr 8 – Apr 22

Carrots, beetsSow outdoors · Apr 15 – Apr 29

TomatoesStart indoors · Mar 11 – Mar 25

TomatoesTransplant · May 13 – May 27

Peppers, eggplantStart indoors · Feb 25 – Mar 11

Peppers, eggplantTransplant · May 20 – Jun 3

BeansSow outdoors · May 13 – May 27

Sweet cornSow outdoors · May 13 – May 27

Cucumbers, squashSow outdoors · May 13 – May 27

Fall lettuce, spinachSow outdoors · Aug 14 – Aug 28

GarlicPlant cloves · Sep 25 – Oct 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 6) and first fall frost (Oct 9) 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 67738 came on Feb 22 — 25 days earlier than the 1991–2020 average (Mar 19).

average
Mar 192026
Feb 22

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 Grinnell, KS.

Soil in Grinnell, KS

The soil mapped at the center of ZIP 67738 is Ulysses — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH7.4slightly alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.8%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Ulysses silt loam, 1 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 67738; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Grinnell, KS

Summer high92 °Faverage high, July

Winter low16 °Faverage low, January

Hot days60days a year at 90 °F or more

Freezing nights162nights a year at 32 °F or less

Growing degree days3,364base 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

Precipitation21.6 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: Oakley 4w, KS (17 mi away); precipitation: Grinnell 4.3 Ssw, KS (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

677376a

Grainfield, KS · 10 mi

Kansas planting zones →

Questions about 67738

What planting zone is ZIP code 67738?

ZIP code 67738 (Grinnell, 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 Grinnell, KS?

The median last spring frost (32 °F) near 67738 is May 6; after May 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Oakley 4w station.

When is the first frost in Grinnell, KS?

The median first fall frost near 67738 is October 9, giving a median frost-free growing season of 156 days.

When should I plant tomatoes in 67738?

Start tomato seeds indoors around Mar 11 – Mar 25 and set transplants outside around May 13 – May 27, one to three weeks after the median last frost.

How much rain and snow does 67738 get?

About 21.6 inches of precipitation a year (NOAA 1991–2020 normals, Grinnell 4.3 Ssw station).

How hot do summers get in Grinnell, KS?

The average high peaks at 92 °F in July, with about 60 days a year at 90 °F or more.

What kind of soil does 67738 have?

The USDA soil survey maps Ulysses at the center of ZIP 67738: silt loam, well drained, pH about 7.4 (slightly alkaline).

Did spring come early in Grinnell, KS in 2026?

Spring leaf-out near 67738 came on Feb 22 in 2026, 25 days earlier than the 1991–2020 average (Mar 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Grinnell, KS?

Intermediate onions: the longest day near 67738 is 14 h 54 min, so day-neutral types bulb best; long-day varieties may not bulb fully.