What USDA hardiness zone is Oklahoma?

Oklahoma spans USDA hardiness zones 6b to 8a, from the USDA 2023 Plant Hardiness Zone Map. 58% of its 662 ZIP codes are zone 7b, so there is no single zone for the state.

When is the last spring frost in Oklahoma?

The median last spring freeze runs March 15 – April 26 across the 193 NOAA stations in Oklahoma with ordinary freeze windows, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

State guide

Planting zones in Oklahoma

Oklahoma spans USDA zones 6b to 8a across its 662 ZIP codes, so there is no single zone for the state and anyone who gives you one is rounding. 58% of its ZIP codes are zone 7b; the rest are not.

USDA zones 6b–8a 4 zones across the state

ZIP codes 662 662 have a NOAA station within range

Weather stations 193 In Oklahoma, NOAA 1991–2020 normals

Your ZIP code

Get the exact answer for your address

Everything above describes Oklahoma as a whole. Hardiness zones and freeze dates are published per ZIP code, so yours is exact — enter it and this page will tell you your zone, which NOAA station it comes from and how far away that station is.

Which zone you are in depends where you are

Oklahoma covers 4 hardiness zones. A guide that gives the state one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 58% in zone 7b and wrong for the other 42%. Here is the actual split, by ZIP code.

Zone	ZIP codes	Share
7b	382	58%
7a	166	25%
8a	99	15%
6b	15	2%

Zones are published per ZIP code, so yours is exact even though the state's is not. The hardiness tool will tell you which one you are in.

Your freeze dates

Last spring freeze March 15 – April 26

First fall freeze October 17 – November 15

Those are the earliest and latest medians among the 193 stations in Oklahoma with an ordinary freeze window — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.

Your growing season

NOAA publishes a growing-season length for each station, and across the 193 stations in Oklahoma it runs 173–244 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 88–96 °F , reaching the 90 °F point where cool-season crops bolt and tomato and pepper pollen fails — so midsummer sowings of lettuce and its relatives are worth holding in the hotter parts of the state.

The ends of each range, named

A range with no station behind it cannot be checked, and Oklahoma has too many stations to table them all. So every figure above is reported here with the station standing at each end of it, by name and NOAA ID. No station on this page represents Oklahoma — these are its edges, which is a different claim.

Measure	Earliest / lowest	Station	Latest / highest	Station
Last spring freeze	March 15	Ardmore, OK USC00340292	April 26	Boise City 2 E, OK USC00340908
First fall freeze	October 17	Boise City 2 E, OK USC00340908	November 15	Hugo, OK USC00344384
Growing season	173 days	Boise City 2 E, OK USC00340908	244 days	Hugo, OK USC00344384
Mean summer high	88 °F	Stilwell 5 Nnw, OK USC00348506	96 °F	Grandfield 3W Mesonet, OK USC00343707

These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.

When to start seeds in Oklahoma

Every spring job for 63 crop dates, counted from this state's own last spring freeze. Each is a range across all 193 stations — the earliest and latest that job falls anywhere in Oklahoma — because no one station speaks for a whole state. The ranges are wide on purpose: that width is the state.

Crop	Job	When	Offset
Green Onions	Start indoors	January 18 – March 1	8 weeks before
Peppers	Start indoors	January 18 – March 1	8 weeks before
Broccoli	Start indoors	February 1 – March 15	6 weeks before
Cabbage	Start indoors	February 1 – March 15	6 weeks before
Collards	Start indoors	February 1 – March 15	6 weeks before
Kale	Start indoors	February 1 – March 15	6 weeks before
Leaf Lettuce	Start indoors	February 1 – March 15	6 weeks before
Peas	Direct sow	February 1 – March 15	6 weeks before
Spinach	Direct sow	February 1 – March 15	6 weeks before
Sweet Potato	Start indoors	February 1 – March 15	6 weeks before
Tomatoes	Start indoors	February 1 – March 15	6 weeks before
Bok Choy	Start indoors	February 8 – March 22	5 weeks before
Kohlrabi	Start indoors	February 8 – March 22	5 weeks before
Swiss Chard	Start indoors	February 8 – March 22	5 weeks before
Arugula	Direct sow	February 15 – March 29	4 weeks before
Baby Salad Greens	Direct sow	February 15 – March 29	4 weeks before
Beets	Direct sow	February 15 – March 29	4 weeks before
Green Onions	Direct sow	February 15 – March 29	4 weeks before
Mustard Greens	Direct sow	February 15 – March 29	4 weeks before
Okra	Start indoors	February 15 – March 29	4 weeks before
Radishes	Direct sow	February 15 – March 29	4 weeks before
Turnips	Direct sow	February 15 – March 29	4 weeks before
Cabbage	Set out	February 22 – April 5	3 weeks before
Carrots	Direct sow	February 22 – April 5	3 weeks before
Collards	Direct sow	February 22 – April 5	3 weeks before
Collards	Set out	February 22 – April 5	3 weeks before
Cucumbers	Start indoors	February 22 – April 5	3 weeks before
Green Onions	Set out	February 22 – April 5	3 weeks before
Kale	Direct sow	February 22 – April 5	3 weeks before
Kale	Set out	February 22 – April 5	3 weeks before
Kohlrabi	Direct sow	February 22 – April 5	3 weeks before
Kohlrabi	Set out	February 22 – April 5	3 weeks before
Leaf Lettuce	Direct sow	February 22 – April 5	3 weeks before
Pumpkins	Start indoors	February 22 – April 5	3 weeks before
Summer Squash	Start indoors	February 22 – April 5	3 weeks before
Winter Squash	Start indoors	February 22 – April 5	3 weeks before
Zucchini	Start indoors	February 22 – April 5	3 weeks before
Bok Choy	Direct sow	March 1 – April 12	2 weeks before
Bok Choy	Set out	March 1 – April 12	2 weeks before
Broccoli	Set out	March 1 – April 12	2 weeks before
Cilantro	Direct sow	March 1 – April 12	2 weeks before
Leaf Lettuce	Set out	March 1 – April 12	2 weeks before
Swiss Chard	Direct sow	March 1 – April 12	2 weeks before
Swiss Chard	Set out	March 1 – April 12	2 weeks before
Dill	Direct sow	March 8 – April 19	1 week before
Bush Beans	Direct sow	March 22 – May 3	1 week after
Cucumbers	Set out	March 22 – May 3	1 week after
Pumpkins	Direct sow	March 22 – May 3	1 week after
Pumpkins	Set out	March 22 – May 3	1 week after
Summer Squash	Direct sow	March 22 – May 3	1 week after
Summer Squash	Set out	March 22 – May 3	1 week after
Sweet Corn	Direct sow	March 22 – May 3	1 week after
Tomatoes	Set out	March 22 – May 3	1 week after
Winter Squash	Direct sow	March 22 – May 3	1 week after
Winter Squash	Set out	March 22 – May 3	1 week after
Zucchini	Direct sow	March 22 – May 3	1 week after
Zucchini	Set out	March 22 – May 3	1 week after
Cucumbers	Direct sow	March 29 – May 10	2 weeks after
Okra	Direct sow	March 29 – May 10	2 weeks after
Okra	Set out	March 29 – May 10	2 weeks after
Peppers	Set out	March 29 – May 10	2 weeks after
Southern Peas	Direct sow	March 29 – May 10	2 weeks after
Sweet Potato	Set out	March 29 – May 10	2 weeks after

The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.

What survives the winter changes across Oklahoma

Of 74 perennial fruits, nuts, berries, vegetables and herbs, 58 come through the winter in zone 7a and only 51 in zone 6b. Winter hardiness runs on the zone alone, so each row below is exact for the ZIP codes in it.

Zone	ZIPs	Survive	Fail for being too warm
6b	15	51 of 74	0
7a	166	58 of 74	1
7b	382	56 of 74	3
8a	99	57 of 74	8

The best zone in Oklahoma is 7a, which is not its mildest — 8a is. The count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat rather than to cold. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the heat that comes with it. See the full list with reasons.

Your own ZIP

Work out your own dates

Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.

What survives my winter?
Runs on the hardiness zone, so it answers exactly for your ZIP code rather than for Oklahoma as a whole — 74 perennial fruits, berries, vegetables and herbs.
When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.

Metro areas in Oklahoma

5 metro areas here have its own page, with the freeze dates from every station serving it, a spring calendar built from those stations, and every ZIP code in it listed with that ZIP code's exact zone and nearest station.

Oklahoma City, OK Zones 7a–7b
Tulsa, OK Zones 7a–7b
Fort Smith, AR-OK Zones 7b–8a
Lawton, OK Zones 7b–8a
Enid, OK Zone 7a

Counties in Oklahoma

33 countys here have its own page, listing every ZIP code in it with that ZIP code's exact zone and nearest station. These are the smaller places outside the metro areas above — where most of Oklahoma's ZIP codes actually are.

Other states to compare

All 52 states · All 388 metro areas · All county pages

Gear

If you want to act on this

Each link opens an Amazon search rather than a product we picked. We have not tested these and do not rank them — the search is the honest version, and you choose.

Shade clothSummer highs here average 92 °F, at or above the 90 °F point where lettuce and spinach bolt and tomato pollen fails.
Row cover and frost clothThe season here closes at the first fall freeze dated above — a cover buys back some of those days at the end.
MulchFor the perennials nearest their cold limit in zone 6b, where an insulated crown is what decides whether they come back.

As an Amazon Associate we earn from qualifying purchases. That costs you nothing extra, and it buys no influence over anything on this site: the dates come from NOAA normals and the zones from the USDA, and no product affects either.

Sources

Where these numbers come from

The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates, growing seasons and summer highs are NOAA's 1991–2020 Climate Normals, read from every station in Oklahoma. Which ZIP codes are in Oklahoma comes from the Census ZIP-to-county relation, since a county's federal code begins with its state's. Nothing here is estimated.

This page names no single station for Oklahoma on purpose. Picking one to represent a state sounds reasonable and is not — the same reason the metro pages refuse it, only more so at this size. Instead every range names the station at each end, so you can check both without either one being made to speak for the state.

All states · All metro areas