What USDA hardiness zone is Richland County, Wisconsin?

Richland County, Wisconsin spans USDA hardiness zones 4b to 5a. 83% of its ZIP codes are zone 5a, so there is no single zone for the county.

When is the last spring frost in Richland County, Wisconsin?

The median last spring freeze runs April 30 – May 12 across the 5 NOAA weather stations serving Richland County, Wisconsin, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

Wisconsin

Planting zones in Richland County, Wisconsin

This county spans USDA zones 4b to 5a, so there is no single zone for Richland County and anyone who gives you one is rounding. 83% of its ZIP codes are zone 5a; the rest are not.

USDA zones 4b–5a 2 zones across 6 ZIP codes

ZIP codes 6 6 have a NOAA station within range

Weather stations 5 NOAA 1991–2020 normals, across 586 sq mi

Your ZIP code

Get the exact answer for your address

Everything above describes Richland County, Wisconsin 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 Richland County is closing

Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 29 – October 9 across the 5 NOAA stations serving this county .

Your next season already has a date

The first job of it is 🧅 Green Onions, start indoors, around March 5 – March 17 — counted back from a last spring freeze of April 30 – May 12 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 5 stations agreeAt least one station

Every one of the 5 NOAA stations serving this county counts May 12 – September 29 as growing season (140 days). Widening to any single station gives April 30 – October 9 (162 days).

That is a 22-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

Richland 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 83% in zone 5a and wrong for the other 17%. Here is the actual split.

Zone	ZIP codes	Share
5a	5	83%
4b	1	17%

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 April 30 – May 12

First fall freeze September 29 – October 9

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 138–161 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 77.3–82.9 °F in June–August. Summer rain over the same months runs 13.1–16.0" 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. At the middle station that is covered, so watering in Richland County is for the gaps between storms rather than the whole season. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 80 °F summer afternoon drying the soil faster than a cool one.

Every ZIP code in Richland 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
53518	5a	Boscobel AP, WI	11.6 km
53556	5a	Lone Rock Tri Co AP, WI	6.0 km
53581	5a	Richland Ctr, WI	5.6 km
53584	4b	Richland Ctr, WI	9.6 km
53924	5a	Hillsboro 2Sw, WI	19.3 km
54664	5a	Viroqua, WI	20.4 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 Richland 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	March 5 – March 17	8 wk before
🌶️ Peppers	Start indoors	March 5 – March 17	8 wk before
🥦 Broccoli	Start indoors	March 19 – March 31	6 wk before
🥬 Cabbage	Start indoors	March 19 – March 31	6 wk before
🥬 Collards	Start indoors	March 19 – March 31	6 wk before
🥬 Kale	Start indoors	March 19 – March 31	6 wk before
🥬 Leaf Lettuce	Start indoors	March 19 – March 31	6 wk before
🫛 Peas	Direct sow	March 19 – March 31	6 wk before
🥬 Spinach	Direct sow	March 19 – March 31	6 wk before
🍠 Sweet Potato	Start indoors	March 19 – March 31	6 wk before
🍅 Tomatoes	Start indoors	March 19 – March 31	6 wk before
🥬 Bok Choy	Start indoors	March 26 – April 7	5 wk before
🥬 Kohlrabi	Start indoors	March 26 – April 7	5 wk before
🥬 Swiss Chard	Start indoors	March 26 – April 7	5 wk before
🥬 Arugula	Direct sow	April 2 – April 14	4 wk before
🥬 Baby Salad Greens	Direct sow	April 2 – April 14	4 wk before
🥕 Beets	Direct sow	April 2 – April 14	4 wk before
🧅 Green Onions	Direct sow	April 2 – April 14	4 wk before
🥬 Mustard Greens	Direct sow	April 2 – April 14	4 wk before
🌶️ Okra	Start indoors	April 2 – April 14	4 wk before
🌱 Radishes	Direct sow	April 2 – April 14	4 wk before
🥔 Turnips	Direct sow	April 2 – April 14	4 wk before
🥬 Cabbage	Set out	April 9 – April 21	3 wk before
🥕 Carrots	Direct sow	April 9 – April 21	3 wk before
🥬 Collards	Direct sow	April 9 – April 21	3 wk before
🥬 Collards	Set out	April 9 – April 21	3 wk before
🥒 Cucumbers	Start indoors	April 9 – April 21	3 wk before
🧅 Green Onions	Set out	April 9 – April 21	3 wk before
🥬 Kale	Direct sow	April 9 – April 21	3 wk before
🥬 Kale	Set out	April 9 – April 21	3 wk before
🥬 Kohlrabi	Direct sow	April 9 – April 21	3 wk before
🥬 Kohlrabi	Set out	April 9 – April 21	3 wk before
🥬 Leaf Lettuce	Direct sow	April 9 – April 21	3 wk before
🎃 Pumpkins	Start indoors	April 9 – April 21	3 wk before
🎃 Summer Squash	Start indoors	April 9 – April 21	3 wk before
🎃 Winter Squash	Start indoors	April 9 – April 21	3 wk before
🥒 Zucchini	Start indoors	April 9 – April 21	3 wk before
🥬 Bok Choy	Direct sow	April 16 – April 28	2 wk before
🥬 Bok Choy	Set out	April 16 – April 28	2 wk before
🥦 Broccoli	Set out	April 16 – April 28	2 wk before
🌿 Cilantro	Direct sow	April 16 – April 28	2 wk before
🥬 Leaf Lettuce	Set out	April 16 – April 28	2 wk before
🥬 Swiss Chard	Direct sow	April 16 – April 28	2 wk before
🥬 Swiss Chard	Set out	April 16 – April 28	2 wk before
🌿 Dill	Direct sow	April 23 – May 5	1 wk before
🫘 Bush Beans	Direct sow	May 7 – May 19	1 wk after
🥒 Cucumbers	Set out	May 7 – May 19	1 wk after
🎃 Pumpkins	Direct sow	May 7 – May 19	1 wk after
🎃 Pumpkins	Set out	May 7 – May 19	1 wk after
🎃 Summer Squash	Direct sow	May 7 – May 19	1 wk after
🎃 Summer Squash	Set out	May 7 – May 19	1 wk after
🌽 Sweet Corn	Direct sow	May 7 – May 19	1 wk after
🍅 Tomatoes	Set out	May 7 – May 19	1 wk after
🎃 Winter Squash	Direct sow	May 7 – May 19	1 wk after
🎃 Winter Squash	Set out	May 7 – May 19	1 wk after
🥒 Zucchini	Direct sow	May 7 – May 19	1 wk after
🥒 Zucchini	Set out	May 7 – May 19	1 wk after
🥒 Cucumbers	Direct sow	May 14 – May 26	2 wk after
🌶️ Okra	Direct sow	May 14 – May 26	2 wk after
🌶️ Okra	Set out	May 14 – May 26	2 wk after
🌶️ Peppers	Set out	May 14 – May 26	2 wk after
🫘 Southern Peas	Direct sow	May 14 – May 26	2 wk after
🍠 Sweet Potato	Set out	May 14 – May 26	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 Richland County

Zone 5a carries 48 of 74 perennial edibles; zone 4b carries 34. 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 May 26 to be careful. Median April 30 – May 12 across 5 stations; April 15 is the optimistic end.
First fall freeze: Plan to September 17 to be careful. Median September 29 – October 9 across 5 stations; October 21 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 53 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
Boscobel AP, WI	USW00094994	May 3	October 7	155 days
Hillsboro 2Sw, WI	USC00473650	May 12	September 29	138 days
Lone Rock Tri Co AP, WI	USW00014921	April 30	October 9	161 days
Richland Ctr, WI	USC00477158	May 5	October 6	154 days
Viroqua, WI	USC00478827	May 7	October 2	148 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

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

More of Wisconsin

Counties with the same zones — 4b–5a

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.

Trunk wrapZone 4b is cold enough that winter sun on a young trunk does more damage than the cold does.
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 4b, 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.