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

Planting zone for 73855 — Rosston, OK

ZIP code 73855 (Rosston, Harper County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 13 and the first fall frost October 28.

Where ZIP 73855 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 13

First frostOct 28

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Rosston, OK…

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 Rosston, OK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 13median — 50% chance of a later frost

Safe for tender plantsApril 27only 10% chance of frost after

First fall frostOctober 28median — 10% chance by Oct 14

Growing season196 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 5.

From the NOAA station Gate, OK — 11 miles away, elevation 2,251 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 73855

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 2 – Mar 16

SpinachSow outdoors · Mar 2 – Mar 23

Broccoli, cabbageStart indoors · Feb 2 – Feb 16

Broccoli, cabbageTransplant · Mar 23 – Apr 6

Onion setsPlant outdoors · Mar 16 – Mar 30

PotatoesPlant outdoors · Mar 23 – Apr 6

LettuceSow outdoors · Mar 16 – Mar 30

Carrots, beetsSow outdoors · Mar 23 – Apr 6

TomatoesStart indoors · Feb 16 – Mar 2

TomatoesTransplant · Apr 20 – May 4

Peppers, eggplantStart indoors · Feb 2 – Feb 16

Peppers, eggplantTransplant · Apr 27 – May 11

BeansSow outdoors · Apr 20 – May 4

Sweet cornSow outdoors · Apr 20 – May 4

Cucumbers, squashSow outdoors · Apr 20 – May 4

Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16

GarlicPlant cloves · Oct 14 – Nov 18

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 13) and first fall frost (Oct 28) 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 73855 came on Feb 15 — 16 days earlier than the 1991–2020 average (Mar 3).

average
Mar 32026
Feb 15

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 7a in Oklahoma

511 plants native to the lower 48 states, recorded in Oklahoma, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 Rosston, OK.

Soil in Rosston, OK

The soil mapped at the center of ZIP 73855 is Oklark — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Oklark-Mansic-Berda complex, 12 to 45 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 73855; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rosston, OK

Summer high94 °Faverage high, July

Winter low22 °Faverage low, January

Hot days79days a year at 90 °F or more

Freezing nights110nights a year at 32 °F or less

Growing degree days4,573base 50 °F — the season’s usable heat

Longest day14 h 41 mindaylight on June 21

Shortest day9 h 38 mindaylight on December 21

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

Precipitation22.6 inper year, rain and melted snow

Snowfall18 inper year; 16 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: Gate, OK (11 mi away); precipitation: Gate, OK (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

678406b

Englewood, KS · 13 mi

Fort Supply, OK · 26 mi

671276b

Protection, KS · 28 mi

Oklahoma planting zones →

Questions about 73855

What planting zone is ZIP code 73855?

ZIP code 73855 (Rosston, OK) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Rosston, OK?

The median last spring frost (32 °F) near 73855 is April 13; after April 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Gate station.

When is the first frost in Rosston, OK?

The median first fall frost near 73855 is October 28, giving a median frost-free growing season of 196 days.

When should I plant tomatoes in 73855?

Start tomato seeds indoors around Feb 16 – Mar 2 and set transplants outside around Apr 20 – May 4, one to three weeks after the median last frost.

How much rain and snow does 73855 get?

About 22.6 inches of precipitation a year and 18 inches of snowfall (NOAA 1991–2020 normals, Gate station).

How hot do summers get in Rosston, OK?

The average high peaks at 94 °F in July, with about 79 days a year at 90 °F or more.

What kind of soil does 73855 have?

The USDA soil survey maps Oklark at the center of ZIP 73855: sandy loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Rosston, OK in 2026?

Spring leaf-out near 73855 came on Feb 15 in 2026, 16 days earlier than the 1991–2020 average (Mar 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rosston, OK?

Intermediate onions: the longest day near 73855 is 14 h 41 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 73855 change?

Yes. The 2012 USDA map put 73855 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.