What USDA hardiness zone is Belknap County, New Hampshire?

Every ZIP code in Belknap County, New Hampshire is USDA hardiness zone 5b, from the USDA 2023 Plant Hardiness Zone Map.

When is the last spring frost in Belknap County, New Hampshire?

The median last spring freeze runs April 28 – May 8 across the 4 NOAA weather stations serving Belknap County, New Hampshire, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

New Hampshire

Planting zones in Belknap County, New Hampshire

Every ZIP code in this county is USDA zone 5b — 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 5b The same in all 13 ZIP codes

ZIP codes 13 13 have a NOAA station within range

Weather stations 4 NOAA 1991–2020 normals, across 402 sq mi

Your ZIP code

Get the exact answer for your address

Everything above describes Belknap County, New Hampshire 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 Belknap County is closing

Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives October 3 – October 18 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 March 3 – March 13 — counted back from a last spring freeze of April 28 – May 8 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 May 8 – October 3 as growing season (148 days). Widening to any single station gives April 28 – October 18 (173 days).

That is a 25-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 April 28 – May 8

First fall freeze October 3 – October 18

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 146–171 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 78.5–80.8 °F in June–August. Summer rain over the same months runs 11.0–12.9" across those 4 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 98% 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 80 °F summer afternoon drying the soil faster than a cool one.

Every ZIP code in Belknap 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
03218	5b	Concord Muni AP, NH	24.2 km
03220	5b	Lakeport 2, NH	8.4 km
03225	5b	Lakeport 2, NH	27.3 km
03226	5b	Meredith 3 Nne, NH	3.2 km
03237	5b	Lakeport 2, NH	14.5 km
03246	5b	Lakeport 2, NH	3.4 km
03249	5b	Lakeport 2, NH	7.9 km
03253	5b	Meredith 3 Nne, NH	7.2 km
03256	5b	Meredith 3 Nne, NH	15.0 km
03269	5b	Franklin Falls Dam, NH	7.8 km
03809	5b	Lakeport 2, NH	23.3 km
03810	5b	Lakeport 2, NH	14.3 km
03837	5b	Lakeport 2, NH	17.5 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 Belknap 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	March 3 – March 13	8 wk before
🌶️ Peppers	Start indoors	March 3 – March 13	8 wk before
🥦 Broccoli	Start indoors	March 17 – March 27	6 wk before
🥬 Cabbage	Start indoors	March 17 – March 27	6 wk before
🥬 Collards	Start indoors	March 17 – March 27	6 wk before
🥬 Kale	Start indoors	March 17 – March 27	6 wk before
🥬 Leaf Lettuce	Start indoors	March 17 – March 27	6 wk before
🫛 Peas	Direct sow	March 17 – March 27	6 wk before
🥬 Spinach	Direct sow	March 17 – March 27	6 wk before
🍠 Sweet Potato	Start indoors	March 17 – March 27	6 wk before
🍅 Tomatoes	Start indoors	March 17 – March 27	6 wk before
🥬 Bok Choy	Start indoors	March 24 – April 3	5 wk before
🥬 Kohlrabi	Start indoors	March 24 – April 3	5 wk before
🥬 Swiss Chard	Start indoors	March 24 – April 3	5 wk before
🥬 Arugula	Direct sow	March 31 – April 10	4 wk before
🥬 Baby Salad Greens	Direct sow	March 31 – April 10	4 wk before
🥕 Beets	Direct sow	March 31 – April 10	4 wk before
🧅 Green Onions	Direct sow	March 31 – April 10	4 wk before
🥬 Mustard Greens	Direct sow	March 31 – April 10	4 wk before
🌶️ Okra	Start indoors	March 31 – April 10	4 wk before
🌱 Radishes	Direct sow	March 31 – April 10	4 wk before
🥔 Turnips	Direct sow	March 31 – April 10	4 wk before
🥬 Cabbage	Set out	April 7 – April 17	3 wk before
🥕 Carrots	Direct sow	April 7 – April 17	3 wk before
🥬 Collards	Direct sow	April 7 – April 17	3 wk before
🥬 Collards	Set out	April 7 – April 17	3 wk before
🥒 Cucumbers	Start indoors	April 7 – April 17	3 wk before
🧅 Green Onions	Set out	April 7 – April 17	3 wk before
🥬 Kale	Direct sow	April 7 – April 17	3 wk before
🥬 Kale	Set out	April 7 – April 17	3 wk before
🥬 Kohlrabi	Direct sow	April 7 – April 17	3 wk before
🥬 Kohlrabi	Set out	April 7 – April 17	3 wk before
🥬 Leaf Lettuce	Direct sow	April 7 – April 17	3 wk before
🎃 Pumpkins	Start indoors	April 7 – April 17	3 wk before
🎃 Summer Squash	Start indoors	April 7 – April 17	3 wk before
🎃 Winter Squash	Start indoors	April 7 – April 17	3 wk before
🥒 Zucchini	Start indoors	April 7 – April 17	3 wk before
🥬 Bok Choy	Direct sow	April 14 – April 24	2 wk before
🥬 Bok Choy	Set out	April 14 – April 24	2 wk before
🥦 Broccoli	Set out	April 14 – April 24	2 wk before
🌿 Cilantro	Direct sow	April 14 – April 24	2 wk before
🥬 Leaf Lettuce	Set out	April 14 – April 24	2 wk before
🥬 Swiss Chard	Direct sow	April 14 – April 24	2 wk before
🥬 Swiss Chard	Set out	April 14 – April 24	2 wk before
🌿 Dill	Direct sow	April 21 – May 1	1 wk before
🫘 Bush Beans	Direct sow	May 5 – May 15	1 wk after
🥒 Cucumbers	Set out	May 5 – May 15	1 wk after
🎃 Pumpkins	Direct sow	May 5 – May 15	1 wk after
🎃 Pumpkins	Set out	May 5 – May 15	1 wk after
🎃 Summer Squash	Direct sow	May 5 – May 15	1 wk after
🎃 Summer Squash	Set out	May 5 – May 15	1 wk after
🌽 Sweet Corn	Direct sow	May 5 – May 15	1 wk after
🍅 Tomatoes	Set out	May 5 – May 15	1 wk after
🎃 Winter Squash	Direct sow	May 5 – May 15	1 wk after
🎃 Winter Squash	Set out	May 5 – May 15	1 wk after
🥒 Zucchini	Direct sow	May 5 – May 15	1 wk after
🥒 Zucchini	Set out	May 5 – May 15	1 wk after
🥒 Cucumbers	Direct sow	May 12 – May 22	2 wk after
🌶️ Okra	Direct sow	May 12 – May 22	2 wk after
🌶️ Okra	Set out	May 12 – May 22	2 wk after
🌶️ Peppers	Set out	May 12 – May 22	2 wk after
🫘 Southern Peas	Direct sow	May 12 – May 22	2 wk after
🍠 Sweet Potato	Set out	May 12 – May 22	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 5b winter

Of 74 perennial edibles, 48 come through a zone 5b winter — and 0 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: Cranberry, Honeyberry, Lingonberry, Apple, Aronia, Black Currant, Elderberry, Gooseberry.

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 22 to be careful. Median April 28 – May 8 across 4 stations; April 15 is the optimistic end.
First fall freeze: Plan to September 21 to be careful. Median October 3 – October 18 across 4 stations; November 3 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 55 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
Concord Muni AP, NH	USW00014745	May 8	October 3	146 days
Franklin Falls Dam, NH	USC00273182	May 7	October 3	148 days
Lakeport 2, NH	USC00274480	April 30	October 18	170 days
Meredith 3 Nne, NH	USC00275350	April 28	October 16	171 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

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

More of New Hampshire

Counties with the same zones — 5b

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 5b 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 5b, 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.