What USDA hardiness zone is Jefferson County, Arkansas?

Jefferson County, Arkansas spans USDA hardiness zones 8a to 8b. 50% of its ZIP codes are zone 8a, so there is no single zone for the county.

When is the last spring frost in Jefferson County, Arkansas?

The median last spring freeze runs March 10 – April 1 across the 5 NOAA weather stations serving Jefferson County, Arkansas, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

Arkansas

Planting zones in Jefferson County, Arkansas

This county spans USDA zones 8a to 8b, so there is no single zone for Jefferson County and anyone who gives you one is rounding. 50% of its ZIP codes are zone 8a; the rest are not.

USDA zones 8a–8b 2 zones across 12 ZIP codes

ZIP codes 12 12 have a NOAA station within range

Weather stations 5 NOAA 1991–2020 normals, across 872 sq mi

Your ZIP code

Get the exact answer for your address

Everything above describes Jefferson County, Arkansas 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.

Jefferson County does not have one planting answer

Its own weather stations disagree about 16 of the 32 crops in this table right now, so any single list would be wrong for part of the county. That is not a gap in the data — it is what the data says.

Shortest season: 218 days
SHERIDAN, AR US (USC00036562)
Longest season: 251 days
ARKANSAS POST, AR US (USC00030240)

33 days of growing season separate those two stations, and both serve ZIP codes in Jefferson County. The ZIP lookup above answers for one address instead of averaging a place that has no average.

Why the hardiness zone does not settle this

A USDA zone is a winter-minimum statistic. It was never a growing-season one, and it does not behave like one: within a single zone the growing season runs a median 54 days wider at the 10th–90th percentile, and annual growing degree days vary by 2.02×.

The zones also overlap rather than stack — 30% of zone 6b freezes before the median zone 6a station. The zone tells you what survives your winter; the station tells you what finishes before your autumn.

The whole dataset behind that →

All 5 stations agreeAt least one station

Every one of the 5 NOAA stations serving this county counts April 1 – November 3 as growing season (216 days). Widening to any single station gives March 10 – November 18 (253 days).

That is a 37-day difference inside one county — which is why this page gives ranges rather than a single planting date. The ZIP lookup above resolves it to one station.

Which zone you are in depends where you are

Jefferson 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 50% in zone 8a and wrong for the other 50%. Here is the actual split.

Zone	ZIP codes	Share
8a	6	50%
8b	6	50%

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 10 – April 1

First fall freeze November 3 – November 18

Across the 5 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 218–251 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 88.4–90.6 °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 9.7–11.3" across those 5 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 79% 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 91 °F summer afternoon drying the soil faster than a cool one.

Every ZIP code in Jefferson 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
71601	8b	Pine Bluff Grider FLD, AR	3.9 km
71602	8a	Pine Bluff, AR	11.8 km
71603	8a	Pine Bluff, AR	13.3 km
71659	8b	Pine Bluff Grider FLD, AR	14.8 km
72004	8b	Pine Bluff, AR	23.6 km
72079	8a	Sheridan, AR	20.5 km
72132	8a	Sheridan, AR	24.1 km
72133	8b	Arkansas Post, AR	15.0 km
72152	8b	Pine Bluff, AR	15.0 km
72168	8a	Keo, AR	18.9 km
72175	8b	Pine Bluff Grider FLD, AR	24.3 km
72182	8a	Keo, AR	21.2 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 Jefferson County

Every date below is anchored on the last spring freeze at each station and reported as a range across all 5 of them, because no one station speaks for the county.

Crop	Job	When	Offset
🧅 Green Onions	Start indoors	January 13 – February 4	8 wk before
🌶️ Peppers	Start indoors	January 13 – February 4	8 wk before
🥦 Broccoli	Start indoors	January 27 – February 18	6 wk before
🥬 Cabbage	Start indoors	January 27 – February 18	6 wk before
🥬 Collards	Start indoors	January 27 – February 18	6 wk before
🥬 Kale	Start indoors	January 27 – February 18	6 wk before
🥬 Leaf Lettuce	Start indoors	January 27 – February 18	6 wk before
🫛 Peas	Direct sow	January 27 – February 18	6 wk before
🥬 Spinach	Direct sow	January 27 – February 18	6 wk before
🍠 Sweet Potato	Start indoors	January 27 – February 18	6 wk before
🍅 Tomatoes	Start indoors	January 27 – February 18	6 wk before
🥬 Bok Choy	Start indoors	February 3 – February 25	5 wk before
🥬 Kohlrabi	Start indoors	February 3 – February 25	5 wk before
🥬 Swiss Chard	Start indoors	February 3 – February 25	5 wk before
🥬 Arugula	Direct sow	February 10 – March 4	4 wk before
🥬 Baby Salad Greens	Direct sow	February 10 – March 4	4 wk before
🥕 Beets	Direct sow	February 10 – March 4	4 wk before
🧅 Green Onions	Direct sow	February 10 – March 4	4 wk before
🥬 Mustard Greens	Direct sow	February 10 – March 4	4 wk before
🌶️ Okra	Start indoors	February 10 – March 4	4 wk before
🌱 Radishes	Direct sow	February 10 – March 4	4 wk before
🥔 Turnips	Direct sow	February 10 – March 4	4 wk before
🥬 Cabbage	Set out	February 17 – March 11	3 wk before
🥕 Carrots	Direct sow	February 17 – March 11	3 wk before
🥬 Collards	Direct sow	February 17 – March 11	3 wk before
🥬 Collards	Set out	February 17 – March 11	3 wk before
🥒 Cucumbers	Start indoors	February 17 – March 11	3 wk before
🧅 Green Onions	Set out	February 17 – March 11	3 wk before
🥬 Kale	Direct sow	February 17 – March 11	3 wk before
🥬 Kale	Set out	February 17 – March 11	3 wk before
🥬 Kohlrabi	Direct sow	February 17 – March 11	3 wk before
🥬 Kohlrabi	Set out	February 17 – March 11	3 wk before
🥬 Leaf Lettuce	Direct sow	February 17 – March 11	3 wk before
🎃 Pumpkins	Start indoors	February 17 – March 11	3 wk before
🎃 Summer Squash	Start indoors	February 17 – March 11	3 wk before
🎃 Winter Squash	Start indoors	February 17 – March 11	3 wk before
🥒 Zucchini	Start indoors	February 17 – March 11	3 wk before
🥬 Bok Choy	Direct sow	February 24 – March 18	2 wk before
🥬 Bok Choy	Set out	February 24 – March 18	2 wk before
🥦 Broccoli	Set out	February 24 – March 18	2 wk before
🌿 Cilantro	Direct sow	February 24 – March 18	2 wk before
🥬 Leaf Lettuce	Set out	February 24 – March 18	2 wk before
🥬 Swiss Chard	Direct sow	February 24 – March 18	2 wk before
🥬 Swiss Chard	Set out	February 24 – March 18	2 wk before
🌿 Dill	Direct sow	March 3 – March 25	1 wk before
🫘 Bush Beans	Direct sow	March 17 – April 8	1 wk after
🥒 Cucumbers	Set out	March 17 – April 8	1 wk after
🎃 Pumpkins	Direct sow	March 17 – April 8	1 wk after
🎃 Pumpkins	Set out	March 17 – April 8	1 wk after
🎃 Summer Squash	Direct sow	March 17 – April 8	1 wk after
🎃 Summer Squash	Set out	March 17 – April 8	1 wk after
🌽 Sweet Corn	Direct sow	March 17 – April 8	1 wk after
🍅 Tomatoes	Set out	March 17 – April 8	1 wk after
🎃 Winter Squash	Direct sow	March 17 – April 8	1 wk after
🎃 Winter Squash	Set out	March 17 – April 8	1 wk after
🥒 Zucchini	Direct sow	March 17 – April 8	1 wk after
🥒 Zucchini	Set out	March 17 – April 8	1 wk after
🥒 Cucumbers	Direct sow	March 24 – April 15	2 wk after
🌶️ Okra	Direct sow	March 24 – April 15	2 wk after
🌶️ Okra	Set out	March 24 – April 15	2 wk after
🌶️ Peppers	Set out	March 24 – April 15	2 wk after
🫘 Southern Peas	Direct sow	March 24 – April 15	2 wk after
🍠 Sweet Potato	Set out	March 24 – April 15	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 Jefferson County

Zone 8a carries 57 of 74 perennial edibles; zone 8b carries 54. 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 17 to be careful. Median March 10 – April 1 across 5 stations; February 20 is the optimistic end.
First fall freeze: Plan to October 20 to be careful. Median November 3 – November 18 across 5 stations; December 8 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 5 stations behind these numbers

All 5 NOAA stations whose normals this page quotes, spanning about 64 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
Arkansas Post, AR	USC00030240	March 10	November 18	251 days
Keo, AR	USC00033862	March 21	November 9	235 days
Pine Bluff Grider FLD, AR	USW00093988	March 13	November 13	243 days
Pine Bluff, AR	USC00035754	March 14	November 16	245 days
Sheridan, AR	USC00036562	April 1	November 3	218 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

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

More of Arkansas

Counties with the same zones — 8a–8b

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 91 °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 8a, 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.