Zone 3b

Hardiness Zone 3b

USDA hardiness zone 3b has an average coldest winter night of -35 to -30 °F (-37 to -34 °C). On the 2023 map it covers ZIP codes in 6 states, mostly Minnesota, North Dakota and Alaska. Cities in zone 3b include Bemidji, MN; Virginia, MN; Akiachak, AK.

Average coldest night

-35 to -30 °F

-37 to -34 °C

States with zone 3b

ZIP codes in zone 3b

230

Check your own zone

States in zone 3b

State	ZIP codes	Share of state
Minnesota	123	13%
North Dakota	54	13%
Alaska	26	10%
Montana	25	6%
Maine	1	<1%
Wisconsin	1	<1%

Cities in zone 3b

Larger places where every ZIP code is zone 3b.

Zones: 2023 USDA Plant Hardiness Zone Map ZIP code data, USDA Agricultural Research Service and the PRISM Climate Group, Oregon State University (official map). Place names: GeoNames (CC BY 4.0). Each ZIP code gets one zone, but a ZIP code can cross a zone line, and hills, valleys and towns can be warmer or colder than the zone shown.

About the Hardiness Zone Map

The Hardiness Zone Map finds your USDA plant hardiness zone, also called your planting or growing zone, from your ZIP code. Zones are based on the average coldest winter night of the year: each zone is 10 °F wide and split into a and b halves of 5 °F, from zone 1a in Alaska to 13b in Puerto Rico. Plant labels and seed packets give the coldest zone a plant can survive, so knowing your zone tells you which perennials, shrubs and trees can stay outside all winter. Zones come from the official 2023 USDA map ZIP code data for all 50 states, Washington DC and Puerto Rico.

How to use it

1 Enter your 5-digit ZIP code and press Find my zone.
2 Read your zone and the average coldest winter temperature it stands for.
3 Open your state to see its zones and the zone of every city.
4 Choose plants rated for your zone number or a colder (lower) one.

Frequently asked questions

What is the lowest temperature in zone 3b?

In zone 3b the coldest night of the year averages -35 to -30 °F (-37 to -34 °C). That is an average over 1991–2020, so a hard winter can go lower.

Which states have zone 3b?

Zone 3b is found in Minnesota, North Dakota, Alaska, Montana, Maine and Wisconsin.

What is the difference between zone 3a and 3b?

Zone 3b is 5 °F warmer than 3a. Zone 3a has winter lows of -40 to -35 °F, and zone 3b -35 to -30 °F. Plant labels often give only the number, which covers both halves.

What plants grow in zone 3b?

Plants labelled hardy to zone 3 or colder (a lower number) should survive a zone 3b winter. Plants rated only for warmer zones may be damaged by frost unless grown in pots and brought in, or given shelter.

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