What are gardening (hardiness) zones + 3 ways to find your zone

Because of its value as an indicator of growing conditions and other features, hardiness zone maps have been used for almost a century, dating back to 1927. These maps have evolved over the many decades, increasing from the initial 8 zones to a total of 13 zones, each split into two subzones. 

What is a gardening zone?

“Gardening zone” is the common term for USDA hardiness zones. They are determined by average annual minimum temperature, which creates geospecific zones across the United States. Zones are defined by location and temperature and are a good guide to help you understand what plants will grow successfully in your area, and at what time of the year.

Are there other factors beyond the gardening zone that impact what you can grow?

Microclimates, rainfall, and humidity are other factors that will play a role in the success or failure of your gardening. If you live along a lakefront you may experience temperatures much lower than other people just a few miles away in your same gardening zone. If you live in a desert, you may fall into one zone but have insufficient rainfall to support some plants that typically grow in your zone.

How do I know what plants grow in my zone?

If you are growing plants from seed, the seed packet should indicate what zone it grows in, and at what time of the year you should start it indoors or sow it directly outside.

3 ways to find your hardiness zone

So you need to know what gardening zone you live in to understand what plants will thrive in your garden, but how do you actually do that? There are three easy ways:

Find your gardening zone by temperature

Gardening zones are determined by average temperatures in your area, divided into zones within 10 degrees F. 

If you know your annual average low temperatures, you can use this table to identify your zone. Using this guide can be helpful if you live in a microclimate that has higher or lower temperatures than surrounding areas, because you may be able to better match your zone than you would by zip code.

1a	-60 to -55 °F/-51.1 to -48.3 °C
1b	-55 to -50 °F/-48.3 to -45.6 °C
2a	-50 to -45 °F/-45.6 to -42.8 °C
2b	-45 to -40 °F/-42.8 to -40 °C
3a	-40 to -35 °F/-40 to -37.2 °C
3b	-35 to -30 °F/-37.2 to -34.4 °C
4a	-30 to -25 °F/-34.4 to -31.7 °C
4b	-25 to -20 °F/-31.7 to -28.9 °C
5a	-20 to -15 °F/-28.9 to -26.1 °C
5b	-15 to -10 °F/-26.1 to -23.3 °C
6a	-10 to -5 °F/-23.3 to -20.6 °C
6b	-5 to 0 °F/-20.6 to -17.8 °C
7a	0 to 5 °F/-17.8 to -15 °C
7b	5 to 10 °F/-15 to -12.2 °C
8a	10 to 15 °F/-12.2 to -9.4 °C
8b	15 to 20 °F/-9.4 to -6.7 °C
9a	20 to 25 °F/-6.7 to -3.9 °C
9b	25 to 30 °F/-3.9 to -1.1 °C
10	30 to 35 °F/-1.1 to 1.7 °C
10b	35 to 40 °F/1.7 to 4.4 °C
11a	40 to 45 °F/4.4 to 7.2 °C
11b	45 to 50 °F/7.2 to 10 °C
12a	50 to 55 °F/10 to 12.8 °C
12b	55 to 60 °F/12.8 to 15.6 °C
13a	60 to 65 °F/15.6 to 18.3 °C
13b	65 to 70 °F/18.3 to 21.1 °C

Find your gardening zone by zip code on the USDA website

The USDA website has an easy zone map where you can enter your address or zip code to find out what zone you live in. This is an easy 2-second way to find your growing zone and better understand what plants will grow well in your garden.

Find your location on the gardening zone map

If you’re having trouble using the USDA address finder, you can simply match your location to the map that they provide. 

Gardening zones for 5 popular states in the United States

We can’t list out every state and its respective gardening zones, but here is a quick guide for some of the most popular locations in the US.

What planting zone is Florida?

Florida has four planting zones: 8, 9, 10, and 11. This means cool-weather plants may not succeed in Florida, and hot weather plants should thrive. 

What planting zone is Illinois?

From north to south, Illinois has hardiness zones between 5a-7b. You can expect relatively short summer growing seasons, but cooler weather veggies will thrive during extended springs and falls. 

What planting zone is Iowa?

The majority of the state of Iowa is in zone 5. Some areas in the northeast are zone 6, while the southern part of the state falls in zone 6. 

What planting zone is Arkansas?

The state of Arkansas includes USDA zones ranging from 6-8. Zone 7 dominates the majority of the state, where temperatures tend not to drop below 0 Fahrenheit.