What Growing Zone Is Union?

Our records indicate the United States Department of Agriculture has given Union a growing zone designation of 5a. Sometimes also called the planting or hardiness zone, this zone number gives you an idea of what plants can and cannot grow in Union's climate based on the average extreme annual temperature. .Our data is based on the latest 2023 USDA maps, which used Union's weather data from 1991 - 2020 in their analysis.

If you are looking for plants suitable for growing in the Union area, head on over to our page on plants that grow well in Union, IA.

Raised Garden Bed Kit

Easy-to-assemble raised garden bed for better soil control and drainage.

Brass Watering Can

Elegant brass watering can with classic design and durability.

Metal Arbor Trellis

Decorative arbor trellis for climbing plants and garden entrance.

Large Greenhouse Kit

Spacious greenhouse for extending your growing season.

Small Greenhouse Kit

Compact greenhouse perfect for small spaces.

Latest IA growing zone map

The growing zone is a measure of the lowest temperature that a plant can survive based on average lowest year temperatures, helping you to decide what plants would grow best in your particular climate. Since Union is in growing zone 5a this means that plants there can survive temperatures as low as -20 to -15 degrees Fahrenheit. Plants for Union's climate should be chosen with this in mind, or plants should be moved inside to keep their core temperature in the right range if necessary.

Some zones may have been changed by the USDA as of 2023. To see if the Union area has been affected, refer to this map of half zone changes from the 2012 version of the USDA zones to the 2023 version.

Half zone changes from 2012 to 2023

The updated map shows that over half of the Southeast has warmed by about half a zone. For gardeners, that means you can now grow plants that tolerate a bit more heat and less frost than before. The tan areas reflect this shift. Meanwhile, the white areas had slight temperature changes, but not enough to move them into a new zone. In the Western U.S., a few spots shifted cooler. That’s not due to a colder climate, but because the new map uses a larger dataset, giving a more accurate picture of local conditions. It's important to keep track of these changes when planning your garden!

Union's Growing Zone Details

Metal Seed Storage Box

Organized storage solution for your seed collection.

Worm Composting Kit

Complete kit for starting your own worm composting system.

Hydroponic Garden Grow Kit

Grow fresh herbs and vegetables year-round with this indoor hydroponic garden system.

Brass Watering Can

Elegant brass watering can with classic design and durability.

Hoeing Ain't Easy Garden Sign

Fun and decorative garden sign to add personality to your space.

Map of the Union Area

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Large Greenhouse Kit

Spacious greenhouse for extending your growing season.

Brass Decorative Faucet Handle

Elegant brass handle to enhance your garden faucet.

Rustic Iron Garden Trellis

Sturdy trellis for supporting climbing plants and vines.

Worm Composting Kit

Complete kit for starting your own worm composting system.

Raised Garden Bed Kit

Easy-to-assemble raised garden bed for better soil control and drainage.

Plants For Other States:

Looking for the best plants in a different area of the United States? Click on a button below to find plants that are ideal for that state's temperatures.

Shiitake Mushroom Kit

Grow your own delicious shiitake mushrooms at home.

Metal Arbor Trellis

Decorative arbor trellis for climbing plants and garden entrance.

Reusable Grow Bags

Breathable fabric grow bags that promote healthy root growth for your vegetables and fruits.

Large Greenhouse Kit

Spacious greenhouse for extending your growing season.

Worm Composting Kit

Complete kit for starting your own worm composting system.