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

Planting zone for 73733 — Douglas, OK

ZIP code 73733 (Douglas, Garfield County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 11 and the first fall frost October 31.

Where ZIP 73733 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 11

First frostOct 31

2012 zone7a

Same zone as on the 2012 map. 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 Douglas, 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 Douglas, OK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 11median — 50% chance of a later frost

Safe for tender plantsApril 29only 10% chance of frost after

First fall frostOctober 31median — 10% chance by Oct 16

Growing season201 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 29 and returns around November 7.

From the NOAA station Marshall 3sse Mesonet, OK — 11 miles away, elevation 1,020 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 73733

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 28 – Mar 14

SpinachSow outdoors · Feb 28 – Mar 21

Broccoli, cabbageStart indoors · Jan 31 – Feb 14

Broccoli, cabbageTransplant · Mar 21 – Apr 4

Onion setsPlant outdoors · Mar 14 – Mar 28

PotatoesPlant outdoors · Mar 21 – Apr 4

LettuceSow outdoors · Mar 14 – Mar 28

Carrots, beetsSow outdoors · Mar 21 – Apr 4

TomatoesStart indoors · Feb 14 – Feb 28

TomatoesTransplant · Apr 18 – May 2

Peppers, eggplantStart indoors · Jan 31 – Feb 14

Peppers, eggplantTransplant · Apr 25 – May 9

BeansSow outdoors · Apr 18 – May 2

Sweet cornSow outdoors · Apr 18 – May 2

Cucumbers, squashSow outdoors · Apr 18 – May 2

Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19

GarlicPlant cloves · Oct 17 – Nov 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 11) and first fall frost (Oct 31) 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 73733 came on Feb 14 — 14 days earlier than the 1991–2020 average (Feb 28).

average
Feb 282026
Feb 14

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 Douglas, OK.

Soil in Douglas, OK

The soil mapped at the center of ZIP 73733 is Renthin — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up

pH6.7neutral; 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: Renthin-Masham complex, 3 to 5 percent slopes, eroded.

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 73733; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Douglas, OK

Summer high94 °Faverage high, July

Winter low25 °Faverage low, January

Hot days80days a year at 90 °F or more

Freezing nights95nights a year at 32 °F or less

Growing degree days4,952base 50 °F — the season’s usable heat

Longest day14 h 38 mindaylight on June 21

Shortest day9 h 41 mindaylight on December 21

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

Precipitation34.4 inper year, rain and melted snow

Snowfall4 inper year; 2 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: Marshall 3sse Mesonet, OK (11 mi away); precipitation: Marshall, OK (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

Oklahoma planting zones →

Questions about 73733

What planting zone is ZIP code 73733?

ZIP code 73733 (Douglas, 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 Douglas, OK?

The median last spring frost (32 °F) near 73733 is April 11; after April 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Marshall 3sse Mesonet station.

When is the first frost in Douglas, OK?

The median first fall frost near 73733 is October 31, giving a median frost-free growing season of 201 days.

When should I plant tomatoes in 73733?

Start tomato seeds indoors around Feb 14 – Feb 28 and set transplants outside around Apr 18 – May 2, one to three weeks after the median last frost.

How much rain and snow does 73733 get?

About 34.4 inches of precipitation a year and 4 inches of snowfall (NOAA 1991–2020 normals, Marshall station).

How hot do summers get in Douglas, OK?

The average high peaks at 94 °F in July, with about 80 days a year at 90 °F or more.

What kind of soil does 73733 have?

The USDA soil survey maps Renthin at the center of ZIP 73733: clay loam, well drained, pH about 6.7 (neutral).

Did spring come early in Douglas, OK in 2026?

Spring leaf-out near 73733 came on Feb 14 in 2026, 14 days earlier than the 1991–2020 average (Feb 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Douglas, OK?

Intermediate onions: the longest day near 73733 is 14 h 38 min, so day-neutral types bulb best; long-day varieties may not bulb fully.