Find Your Hardiness Zone - Minnesota State Horticultural Society

One of the most important things us cold-climate gardeners need to know? Our plant hardiness zone. Cold hardiness zones are established by the U.S. Department of Agriculture every 20 years or so. The lower your zone number, the colder it is. Use this handy guide to find the hardiness zone specific to you.

• Map of the hardiness zones of north central U.S. Source: USDA

• The 2023 plant hardiness zone map for the U.S. Source: USDA

The most recent cold hardiness zone map was released in 2023 and most of Minnesota is in USDA Zone 4, which means the extreme low temperature in the zone gets to between -20 F and -30 F. The northern third or so of the state is in zone 3 (-30 to -40). To find out what your hardiness zone is down to the zip code level, check out this handy interactive map from USDA.

Each zone is divided into “a” and “b” zones, each of which has about a 5 degree difference in extreme cold temperatures. So, gardeners in St. Cloud are in USDA Zone 4b (-25), while those in the northern suburbs of the Twin Cities, just 30 miles away are in 5a (-20).

Turning up the heat

A notable change between the last map edition from 2012 to our current 2023 edition is the new inclusion of most of the Twin Cities area in grow zone 5a. As a large urban center, the climate of the Twin Cities area is influenced by the urban heat island effect: a climatology concept where large cities experience slightly warmer temperatures than the surrounding rural areas. This change in temperature is due to high concentration of heat-absorbent surfaces in cities (like asphalt roads) combined with a lower density of plant life, which provide a natural cooling effect.

Why do hardiness zones matter?

Hardiness zones are used by plant companies to establish ratings for their plants so gardeners know whether plant particular species will survive in their area. (Oaks in Minnesota, yes! Crepe Myrtles, no!) When they test new plant introductions around the country, they determine how cold it can get before a plant dies. While some gardeners think plant breeders tend to be too conservative – rating a plant as zone 5b (Iowa, southern Wisconsin, Illinois) when it will survive in Minnesota – hardiness zones are a great guide for determining which perennials, shrubs and trees will survive in your area.

If you happen to live on the cusp of one zone or the other, such as gardeners in Brainerd or Pine County, you need to consider the microclimate of your particular property. Wind breaks, extra sun or shade and a variety of other factors can affect the specific climate in your yard.

Plant tags and hardiness ratings

To determine whether a tree, shrub or perennial will survive in your yard, check the plant tag. Plant tags almost always list the hardiness rating, as do seed packets for perennials. If it’s not on the front, turn the tag over to look at the back side under care instructions. You can plant anything with a plant hardiness zone colder than your zone. So, gardeners in USDA Zone 4 can plant all the zone 3 plants they want. If you are planting zone 5 plants, though, don’t be surprised if it struggles.

• The front of a plant tag for sweet potato vine. The grow zone information can be found on the back.

• The back of a plant tag for sweet potato vine. The grow zone info is found on the center of the tag, between the “spacing” and “fertilize” sections.

Netanya Sadoff is a bold young writer and science educator with a passion for all things gardening. A lifelong plant enthusiast, Netanya is delighted to contribute to Northern Gardener as the Education + Marketing Support Intern for Summer 2025.

@Netanya.rose