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

Planting zone for 73444 — Hennepin, OK

ZIP code 73444 (Hennepin, Garvin County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is April 6 and the first fall frost November 1.

Where ZIP 73444 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.

Zone8a10 to 15 °F

Coldest night−12.2 to −9.4 °C

Last frostApr 6

First frostNov 1

2012 zone7b

Was 7b 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 8a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Hennepin, 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 Hennepin, OK

JanFebMarAprMayJunJulAugSepOctNovDec

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

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

Safe for tender plantsApril 25only 10% chance of frost after

First fall frostNovember 1median — 10% chance by Oct 15

Growing season204 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 28 and returns around November 8.

From the NOAA station Healdton 3 E, OK — 17 miles away, elevation 902 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 73444

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 23 – Mar 9

SpinachSow outdoors · Feb 23 – Mar 16

Broccoli, cabbageStart indoors · Jan 26 – Feb 9

Broccoli, cabbageTransplant · Mar 16 – Mar 30

Onion setsPlant outdoors · Mar 9 – Mar 23

PotatoesPlant outdoors · Mar 16 – Mar 30

LettuceSow outdoors · Mar 9 – Mar 23

Carrots, beetsSow outdoors · Mar 16 – Mar 30

TomatoesStart indoors · Feb 9 – Feb 23

TomatoesTransplant · Apr 13 – Apr 27

Peppers, eggplantStart indoors · Jan 26 – Feb 9

Peppers, eggplantTransplant · Apr 20 – May 4

BeansSow outdoors · Apr 13 – Apr 27

Sweet cornSow outdoors · Apr 13 – Apr 27

Cucumbers, squashSow outdoors · Apr 13 – Apr 27

Fall lettuce, spinachSow outdoors · Sep 6 – Sep 20

GarlicPlant cloves · Oct 18 – Nov 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 6) and first fall frost (Nov 1) 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 73444 came on Feb 11 — 6 days earlier than the 1991–2020 average (Feb 17).

average
Feb 172026
Feb 11

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 8a in Oklahoma

525 plants native to the lower 48 states, recorded in Oklahoma, and rated by the USDA to survive 10 °F or colder — the bottom of zone 8a. 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 Hennepin, OK.

Soil in Hennepin, OK

The soil mapped at the center of ZIP 73444 is Kiti — flaggy silty clay loam, well drained.

TextureFlaggy silty clay loamholds water and nutrients; slow to drain and warm up

pH7.5slightly alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Kiti-Grainola complex, 5 to 20 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 73444; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hennepin, OK

Summer high95 °Faverage high, July

Winter low27 °Faverage low, January

Hot days84days a year at 90 °F or more

Freezing nights74nights a year at 32 °F or less

Growing degree days5,225base 50 °F — the season’s usable heat

Longest day14 h 28 mindaylight on June 21

Shortest day9 h 51 mindaylight on December 21

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

Precipitation38.1 inper year, rain and melted snow

Snowfall3 inper year; 1 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: Healdton 3 E, OK (17 mi away); precipitation: Hennepin 5 N, OK (7 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.

Ratliff City, OK · 9 mi

Countyline, OK · 10 mi

730307b

Davis, OK · 11 mi

Oklahoma planting zones →

Questions about 73444

What planting zone is ZIP code 73444?

ZIP code 73444 (Hennepin, OK) is in USDA hardiness zone 8a on the 2023 map: the coldest night of an average winter reaches 10 to 15 °F (−12.2 to −9.4 °C).

When is the last frost in Hennepin, OK?

The median last spring frost (32 °F) near 73444 is April 6; after April 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Healdton 3 E station.

When is the first frost in Hennepin, OK?

The median first fall frost near 73444 is November 1, giving a median frost-free growing season of 204 days.

When should I plant tomatoes in 73444?

Start tomato seeds indoors around Feb 9 – Feb 23 and set transplants outside around Apr 13 – Apr 27, one to three weeks after the median last frost.

How much rain and snow does 73444 get?

About 38.1 inches of precipitation a year and 3 inches of snowfall (NOAA 1991–2020 normals, Hennepin 5 N station).

How hot do summers get in Hennepin, OK?

The average high peaks at 95 °F in July, with about 84 days a year at 90 °F or more.

What kind of soil does 73444 have?

The USDA soil survey maps Kiti at the center of ZIP 73444: flaggy silty clay loam, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Hennepin, OK in 2026?

Spring leaf-out near 73444 came on Feb 11 in 2026, 6 days earlier than the 1991–2020 average (Feb 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hennepin, OK?

Intermediate onions: the longest day near 73444 is 14 h 28 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 73444 change?

Yes. The 2012 USDA map put 73444 in zone 7b; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.