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

Planting zone for 66536 — Saint Marys, KS

ZIP code 66536 (Saint Marys, Pottawatomie County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 18 and the first fall frost October 19.

Where ZIP 66536 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 18
First frostOct 19
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 Saint Marys, 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 Saint Marys, KS

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 18median — 50% chance of a later frost
Safe for tender plantsMay 2only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 3
Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 8 and returns around October 28.

From the NOAA station Wamego 4 W, KS — 16 miles away, elevation 1,165 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 66536

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 7 – Mar 21
SpinachSow outdoors · Mar 7 – Mar 28
Broccoli, cabbageStart indoors · Feb 7 – Feb 21
Broccoli, cabbageTransplant · Mar 28 – Apr 11
Onion setsPlant outdoors · Mar 21 – Apr 4
PotatoesPlant outdoors · Mar 28 – Apr 11
LettuceSow outdoors · Mar 21 – Apr 4
Carrots, beetsSow outdoors · Mar 28 – Apr 11
TomatoesStart indoors · Feb 21 – Mar 7
TomatoesTransplant · Apr 25 – May 9
Peppers, eggplantStart indoors · Feb 7 – Feb 21
Peppers, eggplantTransplant · May 2 – May 16
BeansSow outdoors · Apr 25 – May 9
Sweet cornSow outdoors · Apr 25 – May 9
Cucumbers, squashSow outdoors · Apr 25 – May 9
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 18) 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 66536 came on Feb 28 — 18 days earlier than the 1991–2020 average (Mar 18).

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.

Trees 37

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Fbitternut hickory75 ft · blooms mid spring · high shade tolerance · to −47 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack maple100 ft · blooms late spring · low shade tolerance · to −47 °F

Shrubs 64

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fblack cherry80 ft · blooms late spring · high shade tolerance · to −33 °Fblackhaw16 ft · blooms spring · low shade tolerance · to −33 °Fblackjack oak25 ft · blooms mid spring · high shade tolerance · to −13 °F

Wildflowers & perennials 176

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °F

Grasses 134

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °F

Vines 11

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °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 Saint Marys, KS.

Soil in Saint Marys, KS

The soil mapped at the center of ZIP 66536 is Tully — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.5neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Tully silty clay loam, 3 to 7 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 66536; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Marys, KS

Summer high90 °Faverage high, July
Winter low18 °Faverage low, January
Hot days49days a year at 90 °F or more
Freezing nights119nights a year at 32 °F or less
Growing degree days4,040base 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
Precipitation36.6 inper year, rain and melted snow
Snowfall10 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 39 °F, low 18 °F 39°18° JanFebruary: average high 45 °F, low 21 °F 45°21° FebMarch: average high 56 °F, low 31 °F 56°31° MarApril: average high 67 °F, low 42 °F 67°42° AprMay: average high 76 °F, low 53 °F 76°53° MayJune: average high 85 °F, low 63 °F 85°63° JunJuly: average high 90 °F, low 68 °F 90°68° JulAugust: average high 89 °F, low 65 °F 89°65° AugSeptember: average high 81 °F, low 56 °F 81°56° SepOctober: average high 69 °F, low 43 °F 69°43° OctNovember: average high 55 °F, low 31 °F 55°31° NovDecember: average high 43 °F, low 22 °F 43°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 0.82 in precipitation, 2.9 in snowfall 0.8❄3 JanFebruary: 1.20 in precipitation, 2.1 in snowfall 1.2❄2 FebMarch: 2.24 in precipitation, 1.3 in snowfall 2.2❄1 MarApril: 3.58 in precipitation 3.6 AprMay: 5.39 in precipitation 5.4 MayJune: 4.46 in precipitation 4.5 JunJuly: 4.53 in precipitation 4.5 JulAugust: 4.54 in precipitation 4.5 AugSeptember: 3.80 in precipitation 3.8 SepOctober: 3.04 in precipitation, 0.2 in snowfall 3.0 OctNovember: 1.66 in precipitation, 1.1 in snowfall 1.7❄1 NovDecember: 1.36 in precipitation, 2 in snowfall 1.4❄2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Wamego 4 W, KS (16 mi away); precipitation: Emmett, KS (6 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.

664076b
Belvue, KS · 6 mi
665336b
Rossville, KS · 7 mi
664226a
Emmett, KS · 8 mi
664186b
Delia, KS · 9 mi
665076b
Maple Hill, KS · 12 mi
665266b
Paxico, KS · 12 mi
665476b
Wamego, KS · 12 mi
665396b
Silver Lake, KS · 13 mi

Kansas planting zones →

Questions about 66536

What planting zone is ZIP code 66536?

ZIP code 66536 (Saint Marys, 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 Saint Marys, KS?

The median last spring frost (32 °F) near 66536 is April 18; after May 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wamego 4 W station.

When is the first frost in Saint Marys, KS?

The median first fall frost near 66536 is October 19, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 66536?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 66536 get?

About 36.6 inches of precipitation a year and 10 inches of snowfall (NOAA 1991–2020 normals, Emmett station).

How hot do summers get in Saint Marys, KS?

The average high peaks at 90 °F in July, with about 49 days a year at 90 °F or more.

What kind of soil does 66536 have?

The USDA soil survey maps Tully at the center of ZIP 66536: silty clay loam, well drained, pH about 6.5 (neutral).

Did spring come early in Saint Marys, KS in 2026?

Spring leaf-out near 66536 came on Feb 28 in 2026, 18 days earlier than the 1991–2020 average (Mar 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Marys, KS?

Intermediate onions: the longest day near 66536 is 14 h 56 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 66536 change?

Yes. The 2012 USDA map put 66536 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.