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

Planting zone for 73851 — May, OK

ZIP code 73851 (May, Harper County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 21 and the first fall frost October 19.

Where ZIP 73851 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 21

First frostOct 19

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 May, 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 May, OK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 21median — 50% chance of a later frost

Safe for tender plantsMay 5only 10% chance of frost after

First fall frostOctober 19median — 10% chance by Oct 4

Growing season179 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around October 28.

From the NOAA station Ft Supply 3se, OK — 14 miles away, elevation 2,031 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 73851

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 10 – Mar 24

SpinachSow outdoors · Mar 10 – Mar 31

Broccoli, cabbageStart indoors · Feb 10 – Feb 24

Broccoli, cabbageTransplant · Mar 31 – Apr 14

Onion setsPlant outdoors · Mar 24 – Apr 7

PotatoesPlant outdoors · Mar 31 – Apr 14

LettuceSow outdoors · Mar 24 – Apr 7

Carrots, beetsSow outdoors · Mar 31 – Apr 14

TomatoesStart indoors · Feb 24 – Mar 10

TomatoesTransplant · Apr 28 – May 12

Peppers, eggplantStart indoors · Feb 10 – Feb 24

Peppers, eggplantTransplant · May 5 – May 19

BeansSow outdoors · Apr 28 – May 12

Sweet cornSow outdoors · Apr 28 – May 12

Cucumbers, squashSow outdoors · Apr 28 – May 12

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 21) 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 73851 came on Feb 13 — 19 days earlier than the 1991–2020 average (Mar 4).

average
Mar 42026
Feb 13

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 May, OK.

Soil in May, OK

The soil mapped at the center of ZIP 73851 is St. Paul — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: St. Paul silt loam, 0 to 1 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 73851; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in May, OK

Summer high94 °Faverage high, July

Winter low20 °Faverage low, January

Hot days77days a year at 90 °F or more

Freezing nights124nights a year at 32 °F or less

Growing degree days4,414base 50 °F — the season’s usable heat

Longest day14 h 40 mindaylight on June 21

Shortest day9 h 39 mindaylight on December 21

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

Precipitation24.5 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: Ft Supply 3se, OK (14 mi away); precipitation: Laverne 6s, OK (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

738417a

Fort Supply, OK · 9 mi

Oklahoma planting zones →

Questions about 73851

What planting zone is ZIP code 73851?

ZIP code 73851 (May, 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 May, OK?

The median last spring frost (32 °F) near 73851 is April 21; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ft Supply 3se station.

When is the first frost in May, OK?

The median first fall frost near 73851 is October 19, giving a median frost-free growing season of 179 days.

When should I plant tomatoes in 73851?

Start tomato seeds indoors around Feb 24 – Mar 10 and set transplants outside around Apr 28 – May 12, one to three weeks after the median last frost.

How much rain and snow does 73851 get?

About 24.5 inches of precipitation a year (NOAA 1991–2020 normals, Laverne 6s station).

How hot do summers get in May, OK?

The average high peaks at 94 °F in July, with about 77 days a year at 90 °F or more.

What kind of soil does 73851 have?

The USDA soil survey maps St. Paul at the center of ZIP 73851: silt loam, well drained, pH about 7.2 (neutral).

Did spring come early in May, OK in 2026?

Spring leaf-out near 73851 came on Feb 13 in 2026, 19 days earlier than the 1991–2020 average (Mar 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in May, OK?

Intermediate onions: the longest day near 73851 is 14 h 40 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 73851 change?

Yes. The 2012 USDA map put 73851 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.