What USDA hardiness zone is Mason County, Washington?

Every ZIP code in Mason County, Washington is USDA hardiness zone 8b, from the USDA 2023 Plant Hardiness Zone Map.

When is the last spring frost in Mason County, Washington?

The median last spring freeze runs March 11 – April 27 across the 5 NOAA weather stations serving Mason County, Washington, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

Washington

Planting zones in Mason County, Washington

Every ZIP code in this county is USDA zone 8b — so unlike most of the places people look up, there is one right answer here and it holds wherever you are in the county.

USDA zone 8b The same in all 9 ZIP codes

ZIP codes 9 9 have a NOAA station within range

Weather stations 5 NOAA 1991–2020 normals, across 960 sq mi

Your ZIP code

Get the exact answer for your address

Everything above describes Mason County, Washington 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.

Mason 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: 175 days
SHELTON SANDERSON FLD, WA US (USW00094227)
Longest season: 254 days
TACOMA NARROWS AP, WA US (USW00094274)

79 days of growing season separate those two stations, and both serve ZIP codes in Mason 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 27 – October 16 as growing season (172 days). Widening to any single station gives March 11 – November 21 (255 days).

That is a 83-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.

Your freeze dates

Last spring freeze March 11 – April 27

First fall freeze October 16 – November 21

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 175–254 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 73.6–76 °F in June–August. Summer rain over the same months runs 2.9–5.2" 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 27% 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 75 °F summer afternoon drying the soil faster than a cool one.

Every ZIP code in Mason 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
98524	8b	Tacoma Narrows AP, WA	22.5 km
98528	8b	Bremerton, WA	21.0 km
98546	8b	Cushman Powerhouse #2, WA	19.3 km
98548	8b	Cushman Powerhouse #2, WA	19.0 km
98555	8b	Cushman Powerhouse #2, WA	19.5 km
98560	8b	Matlock 8 S, WA	18.3 km
98584	8b	Shelton Sanderson FLD, WA	0.9 km
98588	8b	Cushman Powerhouse #2, WA	12.8 km
98592	8b	Cushman Powerhouse #2, WA	7.5 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 Mason 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 14 – March 2	8 wk before
🌶️ Peppers	Start indoors	January 14 – March 2	8 wk before
🥦 Broccoli	Start indoors	January 28 – March 16	6 wk before
🥬 Cabbage	Start indoors	January 28 – March 16	6 wk before
🥬 Collards	Start indoors	January 28 – March 16	6 wk before
🥬 Kale	Start indoors	January 28 – March 16	6 wk before
🥬 Leaf Lettuce	Start indoors	January 28 – March 16	6 wk before
🫛 Peas	Direct sow	January 28 – March 16	6 wk before
🥬 Spinach	Direct sow	January 28 – March 16	6 wk before
🍠 Sweet Potato	Start indoors	January 28 – March 16	6 wk before
🍅 Tomatoes	Start indoors	January 28 – March 16	6 wk before
🥬 Bok Choy	Start indoors	February 4 – March 23	5 wk before
🥬 Kohlrabi	Start indoors	February 4 – March 23	5 wk before
🥬 Swiss Chard	Start indoors	February 4 – March 23	5 wk before
🥬 Arugula	Direct sow	February 11 – March 30	4 wk before
🥬 Baby Salad Greens	Direct sow	February 11 – March 30	4 wk before
🥕 Beets	Direct sow	February 11 – March 30	4 wk before
🧅 Green Onions	Direct sow	February 11 – March 30	4 wk before
🥬 Mustard Greens	Direct sow	February 11 – March 30	4 wk before
🌶️ Okra	Start indoors	February 11 – March 30	4 wk before
🌱 Radishes	Direct sow	February 11 – March 30	4 wk before
🥔 Turnips	Direct sow	February 11 – March 30	4 wk before
🥬 Cabbage	Set out	February 18 – April 6	3 wk before
🥕 Carrots	Direct sow	February 18 – April 6	3 wk before
🥬 Collards	Direct sow	February 18 – April 6	3 wk before
🥬 Collards	Set out	February 18 – April 6	3 wk before
🥒 Cucumbers	Start indoors	February 18 – April 6	3 wk before
🧅 Green Onions	Set out	February 18 – April 6	3 wk before
🥬 Kale	Direct sow	February 18 – April 6	3 wk before
🥬 Kale	Set out	February 18 – April 6	3 wk before
🥬 Kohlrabi	Direct sow	February 18 – April 6	3 wk before
🥬 Kohlrabi	Set out	February 18 – April 6	3 wk before
🥬 Leaf Lettuce	Direct sow	February 18 – April 6	3 wk before
🎃 Pumpkins	Start indoors	February 18 – April 6	3 wk before
🎃 Summer Squash	Start indoors	February 18 – April 6	3 wk before
🎃 Winter Squash	Start indoors	February 18 – April 6	3 wk before
🥒 Zucchini	Start indoors	February 18 – April 6	3 wk before
🥬 Bok Choy	Direct sow	February 25 – April 13	2 wk before
🥬 Bok Choy	Set out	February 25 – April 13	2 wk before
🥦 Broccoli	Set out	February 25 – April 13	2 wk before
🌿 Cilantro	Direct sow	February 25 – April 13	2 wk before
🥬 Leaf Lettuce	Set out	February 25 – April 13	2 wk before
🥬 Swiss Chard	Direct sow	February 25 – April 13	2 wk before
🥬 Swiss Chard	Set out	February 25 – April 13	2 wk before
🌿 Dill	Direct sow	March 4 – April 20	1 wk before
🫘 Bush Beans	Direct sow	March 18 – May 4	1 wk after
🥒 Cucumbers	Set out	March 18 – May 4	1 wk after
🎃 Pumpkins	Direct sow	March 18 – May 4	1 wk after
🎃 Pumpkins	Set out	March 18 – May 4	1 wk after
🎃 Summer Squash	Direct sow	March 18 – May 4	1 wk after
🎃 Summer Squash	Set out	March 18 – May 4	1 wk after
🌽 Sweet Corn	Direct sow	March 18 – May 4	1 wk after
🍅 Tomatoes	Set out	March 18 – May 4	1 wk after
🎃 Winter Squash	Direct sow	March 18 – May 4	1 wk after
🎃 Winter Squash	Set out	March 18 – May 4	1 wk after
🥒 Zucchini	Direct sow	March 18 – May 4	1 wk after
🥒 Zucchini	Set out	March 18 – May 4	1 wk after
🥒 Cucumbers	Direct sow	March 25 – May 11	2 wk after
🌶️ Okra	Direct sow	March 25 – May 11	2 wk after
🌶️ Okra	Set out	March 25 – May 11	2 wk after
🌶️ Peppers	Set out	March 25 – May 11	2 wk after
🫘 Southern Peas	Direct sow	March 25 – May 11	2 wk after
🍠 Sweet Potato	Set out	March 25 – May 11	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 lives through a zone 8b winter

Of 74 perennial edibles, 54 come through a zone 8b winter — and 11 fail here for being too warm rather than too cold, needing more winter chill than this county gets or more heat than they tolerate. Among the ones that work: Apple, Aronia, Elderberry, Asparagus, Horseradish, Sunchoke, Walking Onion, Chives.

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 12 to be careful. Median March 11 – April 27 across 5 stations; February 15 is the optimistic end.
First fall freeze: Plan to October 1 to be careful. Median October 16 – November 21 across 5 stations; December 10 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 47 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
Bremerton, WA	USC00450872	March 29	November 14	227 days
Cushman Powerhouse #2, WA	USC00451939	March 24	November 15	235 days
Matlock 8 S, WA	USC00455086	April 23	October 20	183 days
Shelton Sanderson FLD, WA	USW00094227	April 27	October 16	175 days
Tacoma Narrows AP, WA	USW00094274	March 11	November 21	254 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

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

More of Washington

Counties with the same zones — 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.

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.

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.