What USDA hardiness zone is Tillman County, Oklahoma?

Tillman County, Oklahoma spans USDA hardiness zones 7b to 8a. 86% of its ZIP codes are zone 8a, so there is no single zone for the county.

When is the last spring frost in Tillman County, Oklahoma?

The median last spring freeze runs March 26 – April 3 across the 4 NOAA weather stations serving Tillman County, Oklahoma, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

Oklahoma

Planting zones in Tillman County, Oklahoma

This county spans USDA zones 7b to 8a, so there is no single zone for Tillman County and anyone who gives you one is rounding. 86% of its ZIP codes are zone 8a; the rest are not.

USDA zones 7b–8a 2 zones across 7 ZIP codes

ZIP codes 7 7 have a NOAA station within range

Weather stations 4 NOAA 1991–2020 normals, across 871 sq mi

Your ZIP code

Get the exact answer for your address

Everything above describes Tillman County, 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.

The growing season in Tillman County is closing

Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives November 4 – November 10 across the 4 NOAA stations serving this county .

Your next season already has a date

The first job of it is 🧅 Green Onions, start indoors, around January 29 – February 6 — counted back from a last spring freeze of March 26 – April 3 here.

Every spring date for your ZIP →

These are ranges across the whole county. The ZIP lookup above gives the dates from your own nearest station instead.

All 4 stations agreeAt least one station

Every one of the 4 NOAA stations serving this county counts April 3 – November 4 as growing season (215 days). Widening to any single station gives March 26 – November 10 (229 days).

Which zone you are in depends where you are

Tillman County covers 2 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 86% in zone 8a and wrong for the other 14%. Here is the actual split.

Zone	ZIP codes	Share
8a	6	86%
7b	1	14%

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

Your freeze dates

Last spring freeze March 26 – April 3

First fall freeze November 4 – November 10

Across the 4 NOAA stations serving this county. These are medians — half of years freeze later than the date shown — so treat the later end of each range as the cautious one.

The growing season runs 213–229 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 95.1–95.9 °F in June–August. That is past the point where tomato and pepper pollen fails and cool-season greens bolt, so in this county heat decides as much as frost does. Summer rain over the same months runs 8.6" across those 1 stations, against the rough inch a week — about 13 inches over the same 92 days — that a vegetable garden is usually reckoned to want. The middle station covers about 65% of it, so expect to make up the rest. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 96 °F summer afternoon drying the soil faster than a cool one.

Every ZIP code in Tillman County

Zones are published per ZIP code, not per county, so this is the exact answer rather than the county's average. The station column is the nearest one to that ZIP code's centroid and how far away it is — the same figure the tools use, shown here so you can see which ZIP codes are well covered and which are reaching.

ZIP code	USDA zone	Nearest NOAA station	Distance
73530	8a	Altus Afb, OK	13.8 km
73542	8a	Altus Afb, OK	5.4 km
73546	8a	Grandfield 3W Mesonet, OK	2.6 km
73551	8a	Altus Afb, OK	10.7 km
73553	8a	Grandfield 3W Mesonet, OK	10.8 km
73555	8a	Frederick, OK	13.8 km
73570	7b	Tipton 4S Mesonet, OK	8.6 km

ZIP-code positions are area centroids, so a large rural ZIP code's listed distance is measured from the middle of its area rather than from any particular address in it.

When to start seeds in Tillman County

Every date below is anchored on the last spring freeze at each station and reported as a range across all 4 of them, because no one station speaks for the county.

Crop	Job	When	Offset
🧅 Green Onions	Start indoors	January 29 – February 6	8 wk before
🌶️ Peppers	Start indoors	January 29 – February 6	8 wk before
🥦 Broccoli	Start indoors	February 12 – February 20	6 wk before
🥬 Cabbage	Start indoors	February 12 – February 20	6 wk before
🥬 Collards	Start indoors	February 12 – February 20	6 wk before
🥬 Kale	Start indoors	February 12 – February 20	6 wk before
🥬 Leaf Lettuce	Start indoors	February 12 – February 20	6 wk before
🫛 Peas	Direct sow	February 12 – February 20	6 wk before
🥬 Spinach	Direct sow	February 12 – February 20	6 wk before
🍠 Sweet Potato	Start indoors	February 12 – February 20	6 wk before
🍅 Tomatoes	Start indoors	February 12 – February 20	6 wk before
🥬 Bok Choy	Start indoors	February 19 – February 27	5 wk before
🥬 Kohlrabi	Start indoors	February 19 – February 27	5 wk before
🥬 Swiss Chard	Start indoors	February 19 – February 27	5 wk before
🥬 Arugula	Direct sow	February 26 – March 6	4 wk before
🥬 Baby Salad Greens	Direct sow	February 26 – March 6	4 wk before
🥕 Beets	Direct sow	February 26 – March 6	4 wk before
🧅 Green Onions	Direct sow	February 26 – March 6	4 wk before
🥬 Mustard Greens	Direct sow	February 26 – March 6	4 wk before
🌶️ Okra	Start indoors	February 26 – March 6	4 wk before
🌱 Radishes	Direct sow	February 26 – March 6	4 wk before
🥔 Turnips	Direct sow	February 26 – March 6	4 wk before
🥬 Cabbage	Set out	March 5 – March 13	3 wk before
🥕 Carrots	Direct sow	March 5 – March 13	3 wk before
🥬 Collards	Direct sow	March 5 – March 13	3 wk before
🥬 Collards	Set out	March 5 – March 13	3 wk before
🥒 Cucumbers	Start indoors	March 5 – March 13	3 wk before
🧅 Green Onions	Set out	March 5 – March 13	3 wk before
🥬 Kale	Direct sow	March 5 – March 13	3 wk before
🥬 Kale	Set out	March 5 – March 13	3 wk before
🥬 Kohlrabi	Direct sow	March 5 – March 13	3 wk before
🥬 Kohlrabi	Set out	March 5 – March 13	3 wk before
🥬 Leaf Lettuce	Direct sow	March 5 – March 13	3 wk before
🎃 Pumpkins	Start indoors	March 5 – March 13	3 wk before
🎃 Summer Squash	Start indoors	March 5 – March 13	3 wk before
🎃 Winter Squash	Start indoors	March 5 – March 13	3 wk before
🥒 Zucchini	Start indoors	March 5 – March 13	3 wk before
🥬 Bok Choy	Direct sow	March 12 – March 20	2 wk before
🥬 Bok Choy	Set out	March 12 – March 20	2 wk before
🥦 Broccoli	Set out	March 12 – March 20	2 wk before
🌿 Cilantro	Direct sow	March 12 – March 20	2 wk before
🥬 Leaf Lettuce	Set out	March 12 – March 20	2 wk before
🥬 Swiss Chard	Direct sow	March 12 – March 20	2 wk before
🥬 Swiss Chard	Set out	March 12 – March 20	2 wk before
🌿 Dill	Direct sow	March 19 – March 27	1 wk before
🫘 Bush Beans	Direct sow	April 2 – April 10	1 wk after
🥒 Cucumbers	Set out	April 2 – April 10	1 wk after
🎃 Pumpkins	Direct sow	April 2 – April 10	1 wk after
🎃 Pumpkins	Set out	April 2 – April 10	1 wk after
🎃 Summer Squash	Direct sow	April 2 – April 10	1 wk after
🎃 Summer Squash	Set out	April 2 – April 10	1 wk after
🌽 Sweet Corn	Direct sow	April 2 – April 10	1 wk after
🍅 Tomatoes	Set out	April 2 – April 10	1 wk after
🎃 Winter Squash	Direct sow	April 2 – April 10	1 wk after
🎃 Winter Squash	Set out	April 2 – April 10	1 wk after
🥒 Zucchini	Direct sow	April 2 – April 10	1 wk after
🥒 Zucchini	Set out	April 2 – April 10	1 wk after
🥒 Cucumbers	Direct sow	April 9 – April 17	2 wk after
🌶️ Okra	Direct sow	April 9 – April 17	2 wk after
🌶️ Okra	Set out	April 9 – April 17	2 wk after
🌶️ Peppers	Set out	April 9 – April 17	2 wk after
🫘 Southern Peas	Direct sow	April 9 – April 17	2 wk after
🍠 Sweet Potato	Set out	April 9 – April 17	2 wk after

Offsets are published guidance; the dates they land on are computed from measured NOAA normals. The seed-starting tool does this for your own ZIP code and counts the days.

What survives the winter changes across Tillman County

Zone 8a carries 57 of 74 perennial edibles; zone 7b carries 56. The best number is not always the warmest zone — the count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat, not to cold.

Hardiness ranges are a judgement, published by growers rather than measured; the zone they are compared against is measured. On a warm-end verdict, check with your local extension service — a coastal zone 8 and an inland zone 8 are not the same summer.

Cautious — shortens the seasonMedian across stationsOptimistic

Last spring freeze: Plan to April 22 to be careful. Median March 26 – April 3 across 4 stations; March 8 is the optimistic end.
First fall freeze: Plan to October 20 to be careful. Median November 4 – November 10 across 4 stations; November 27 is the optimistic end.

NOAA publishes these as probabilities, not averages — the middle figure is a median, so half of years fall either side of it. The cautious end is the 10% tail: in roughly nine years in ten the freeze falls on the safe side of it.

The 4 stations behind these numbers

All 4 NOAA stations whose normals this page quotes, spanning about 22 km north to south. Every one is named with its identifier in the station list below — this page does not single one out, because no one station speaks for a whole county.

A relative sketch, not a map with a projection: longitude is adjusted for latitude so the shape is not stretched, and there is no basemap. For the one station nearest a specific address, with its real distance, use the ZIP lookup above.

These are the stations this county's ZIP codes actually cite as nearest — not a claim that each one sits inside its boundary, since a rural ZIP legitimately reaches over it. Every figure above comes from them, and each is named so you can check it.

Station	NOAA ID	Last spring freeze	First fall freeze	Season
Altus Afb, OK	USW00003981	March 26	November 10	229 days
Frederick, OK	USC00343353	April 3	November 4	213 days
Grandfield 3W Mesonet, OK	USC00343707	March 31	November 6	219 days
Tipton 4S Mesonet, OK	USC00348879	April 3	November 6	217 days

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

Your own ZIP

Work out your own dates

This page describes a whole county. Every tool below answers for one ZIP code, which is the grain the underlying data is published at.

Other places to compare

Tillman County sits in Oklahoma. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.

More of Oklahoma

Counties with the same zones — 7b–8a

Matched on the exact zone set, not a dominant zone, so the winter answer on these pages really is the same one as here.

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 96 °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 7b, 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

Hardiness zones are the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. Freeze dates and growing-season lengths are NOAA 1991–2020 Climate Normals, taken per station and cited above by name and NOAA ID.

County boundaries come from the Census ZCTA-to-county relation, which is what places each ZIP code — and which treats parishes, boroughs and census areas as county equivalents. No station is chosen to represent this county: every range above is taken across all of them and the count is stated, because picking one would be a judgement dressed as a measurement.