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

Planting zone for 73450 — Milburn, OK

ZIP code 73450 (Milburn, Johnston County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is March 31 and the first fall frost November 5.

Where ZIP 73450 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 frostMar 31

First frostNov 5

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 Milburn, 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 Milburn, OK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 31median — 50% chance of a later frost

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

First fall frostNovember 5median — 10% chance by Oct 22

Growing season221 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 18 and returns around November 14.

From the NOAA station Coleman 4w, OK — 2 miles away, elevation 748 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 73450

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 17 – Mar 3

SpinachSow outdoors · Feb 17 – Mar 10

Broccoli, cabbageStart indoors · Jan 20 – Feb 3

Broccoli, cabbageTransplant · Mar 10 – Mar 24

Onion setsPlant outdoors · Mar 3 – Mar 17

PotatoesPlant outdoors · Mar 10 – Mar 24

LettuceSow outdoors · Mar 3 – Mar 17

Carrots, beetsSow outdoors · Mar 10 – Mar 24

TomatoesStart indoors · Feb 3 – Feb 17

TomatoesTransplant · Apr 7 – Apr 21

Peppers, eggplantStart indoors · Jan 20 – Feb 3

Peppers, eggplantTransplant · Apr 14 – Apr 28

BeansSow outdoors · Apr 7 – Apr 21

Sweet cornSow outdoors · Apr 7 – Apr 21

Cucumbers, squashSow outdoors · Apr 7 – Apr 21

Fall lettuce, spinachSow outdoors · Sep 10 – Sep 24

GarlicPlant cloves · Oct 22 – Nov 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 31) and first fall frost (Nov 5) 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 73450 came on Feb 10 — 5 days earlier than the 1991–2020 average (Feb 15).

average
Feb 152026
Feb 10

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 Milburn, OK.

Soil in Milburn, OK

The soil mapped at the center of ZIP 73450 is Gasil — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH6.3slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Gasil fine sandy loam, cool, 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 73450; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Milburn, OK

Summer high94 °Faverage high, July

Winter low30 °Faverage low, January

Hot days77days a year at 90 °F or more

Freezing nights62nights a year at 32 °F or less

Growing degree days5,393base 50 °F — the season’s usable heat

Longest day14 h 27 mindaylight on June 21

Shortest day9 h 52 mindaylight on December 21

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

Precipitation44 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: Coleman 4w, OK (2 mi away); precipitation: Coleman 4.6 Wnw, OK (2 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.

734328a

Coleman, OK · 7 mi

734608a

Tishomingo, OK · 8 mi

Connerville, OK · 13 mi

745357b

Clarita, OK · 16 mi

Oklahoma planting zones →

Questions about 73450

What planting zone is ZIP code 73450?

ZIP code 73450 (Milburn, 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 Milburn, OK?

The median last spring frost (32 °F) near 73450 is March 31; after April 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Coleman 4w station.

When is the first frost in Milburn, OK?

The median first fall frost near 73450 is November 5, giving a median frost-free growing season of 221 days.

When should I plant tomatoes in 73450?

Start tomato seeds indoors around Feb 3 – Feb 17 and set transplants outside around Apr 7 – Apr 21, one to three weeks after the median last frost.

How much rain and snow does 73450 get?

About 44 inches of precipitation a year (NOAA 1991–2020 normals, Coleman 4.6 Wnw station).

How hot do summers get in Milburn, 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 73450 have?

The USDA soil survey maps Gasil at the center of ZIP 73450: fine sandy loam, well drained, pH about 6.3 (slightly acidic).

Did spring come early in Milburn, OK in 2026?

Spring leaf-out near 73450 came on Feb 10 in 2026, 5 days earlier than the 1991–2020 average (Feb 15), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Milburn, OK?

Intermediate onions: the longest day near 73450 is 14 h 27 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 73450 change?

Yes. The 2012 USDA map put 73450 in zone 7b; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.