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Planting Zones: Iowa Hardiness Map

USDA Iowa Hardiness Zones: 4b, 5a, 5b, 6a

Iowa Plant Hardiness Zone Map

Iowa, home of the legendary sliced bread, is also known for its production of corn. Thanks to Iowa’s 86,900 farms, Iowa produces more corn than any other state in the United States.  Iowa’s farms also grow a reasonable amount of soybeans.  

Iowa’s massive production of corn and soybeans can be attributed to the climate and hardiness zones of Indiana. Iowa’s climate is classified as humid continental, which means the summers are hot and the winters are cold. Warm and humid summers make the perfect growing conditions for corn and soybeans.  The hardiness zones of Iowa are zones 4b, 5a, 5b, and 6a.

Iowa Planting Zone- A Quick Overview

  • The vast majority of Iowa hardiness zone is 5a.
  • If you live in the northwestern corner of Iowa, from Osceola west to the state line, you live in the 4b or 5a plant hardiness zone.
  • If you live in Sheldon, you live in the 4b hardiness zone.
  • You’ll find the 5b hardiness zone in the very southern half of the state.  Parts of Iowa City are considered 5b.  The winter temperatures in zone 5b can reach as low as -15 degrees Fahrenheit. 
  • If you live in the most southern tip of Lee County, your plant hardiness zone is 6a.  This is the only area listed as 6a in the entire state of Iowa!

Using the Iowa Growing Zones Map

While Iowa is known mostly for its corn and soybean production, rest assured you are not limited to these two crops for your own backyard garden.  To help you determine which plants and crops to plant in your garden, use the USDA Plant Hardiness Zone Map

The USDA Plant Hardiness Zone Map, created in 2012, helps gardeners and growers determine the planting zone of their specific location.  This map is referenced often by backyard gardeners, too, and will give you pertinent information regarding the climate of Iowa.

To decide which planting zone your garden space is in, you need to first know your specific location.  Enter your zip code or address into the search bar of the USDA Plant Hardiness Map.  If your garden space or field does not have a specified address, click on Iowa, and zoom in on your general area.

Once you’ve found your land on the map, use the color-coded legend on the side of the map to evaluate your growing zone.  The majority of Iowa is located in the 5a growing zone, but your area may be in a slightly different zone– either 4b or 5b.

Temperature and growing season length is the only difference between Iowa’s three major planting zones. Statewide, Iowa’s climate is generally humid continental.  However, keep in mind that the microclimate of your space may be different than the surrounding climate. 

Your land’s microclimate could be different due to the presence of pavement making the land warmer or slopes that affect wind patterns.

Iowa: A Humid Climate with Three Major Planting Zones

If you’re an avid gardener, you know the last spring frost in Iowa is generally between mid-April and mid-May, depending on your location. Most gardeners will tell you that it is safe to plant in your hardiness zone after the last expected frost of the spring. 

If you’re unsure of your last expected frost, check with local nurseries or local weather stations.

Corn and soybeans are not the only crops that do well in Iowa’s hardiness zones.  If you want to landscape and add to your curb appeal to your home or office, consider planting bee balm, daylilies, or phlox. 

If you’re looking to plant vegetables, think about tomatoes, peppers, or melons.  Culver’s Garden Center and Greenhouse, a major nursery in Marion, Iowa, suggests planting shade trees such as maples, oaks, and willows.

Trees to Plant in Iowa

USDA Zone 5