Planting zones for iowa

USDA Hardiness Zone Map

Creating an attractive garden means coordinating colors and selecting eye-catching varieties. However, these aesthetics don’t mean much if the weather conditions in your gardening zone will wilt, freeze, or decay tender plants.

Climate maps/planting zone maps, such as the United States Department of Agriculture Hardiness Zone map, show low-temperature extremes by gardening zone. Choose plants best adapted to your planting zone and plant them at the right time to increase your chance of success.

Use climate zone maps as a general guide; many microclimates may exist within a 1-mile radius of your home’s gardening zones. Even within your yard’s climate zone, variations in exposure and topography can affect plants.

In 2012, the USDA updated the climate zone map with newer data and increased technologies. Using the USDA website, you can now access an interactive planting zone map that lets you zoom into an area and view changes in zones by half-mile increments.

There are two zones that aren’t too common—Zone 1 and Zone 2. These zones are just what you think they are—cold, cold, cold—and are found in places like Canada, Alaska, and even Northern Minnesota. Plants that grow in Zone 1 can withstand temperatures below -50 degrees F to -40 degrees F, but most plants can only withstand temperatures in Zones 3 to 10.

Check out plants that are hardy for your zone.

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Zone 3

Most plants native in the U.S. are found within Zones 3 to 10—the toughest of plants can withstand all of these zones. Zone 3 plants can withstand cold temperatures of -40 to -30 degrees F. The upper Midwest states hold most of Zone 3, such as northern parts of Montana, North Dakota, Minnesota, Wisconsin, and Maine.

When to plant: Mid May

Common plants:

  • Goldenrod
  • Wood Fern
  • Foxglove

See more plants that are hardy in the Midwest.

Zone 4

Zone 4 plants can withstand minimum chilled temps from -30 to -20 degrees F. You can find this zone in Montana, Wyoming, North Dakota, South Dakota, Minnesota, Wisconsin, and Eastern states such as Northern New York, New Hampshire, and Maine.

When to plant: Mid May

Common plants:

  • Hydrangea
  • Crabapple Tree
  • Honeysuckle Vine

Check out more plants that are hardy in the Mountain West.

Zone 5

This zone is another friend of the Midwest and Northeastern states, where humidity thrives over summers, and winters can reach as low as -20 to -10 degrees F. You can find Zone 5 in states like Colorado, Nebraska, Iowa, Wisconsin, Illinois, Indiana, Michigan, and New York.

When to plant: Mid April

Common plants:

  • Boston Ivy
  • Delphinium
  • Sycamore Tree

Check out more plants that are hardy in the Northeast.

Zone 6

It’s the middle of the road for Zone 6. You can find this zone from Pacific Northwest states, such as Washington and Oregon, and stretching over the middle of the U.S. in states like Kansas, Missouri, Illinois, and all the way through Ohio. Plants in this zone can withstand temperatures of -10 to 0 degrees F.

When to plant: Mid April

Common plants:

  • English Ivy
  • Coralbells
  • Weeping Willow

Check out more plants that are hardy in the Pacific Northwest.

Zone 7

Winters usually don’t hit the negatives in this zone. Plants in Zone 7 can handle temperatures of 0 to 10 degrees F. You can find this zone in upper parts of the West (Washington, Oregon) and down through upper Texas, Oklahoma, and all the way through Virgina and North Carolina.

When to plant: Mid April

Common plants:

  • Bleeding Heart
  • Texas Rock Rose
  • Magnolia Tree

Zone 8

Things are starting to heat up in Zone 8. In this zone, native plants are loving the warmth. Not only that, but plants will start to have a longer growing season in Zone 8. You can find this zone consuming the West Coast and most of the South, such as Texas, Louisiana, Mississippi, Alabama, Georgia, and the Carolinas.

When to plant: Mid March

Common plants:

  • Yucca
  • Hibiscus
  • Texas Mountain Laurel

Check out more plants that are hardy in the Desert Southwest.

Zone 9

It’s pure California dreaming with hot and heavy temperatures hitting this zone. These plants can withstand temperatures as low as 20 to 30 degrees F but thrive in 70-90 degree temperatures. You can find Zone 9 consuming California’s landscape, along with Southern Texas, Louisiana, and Florida.

When to plant: Mid February

Common plants:

  • Dahlia
  • Fuchsia
  • Sweetshade Tree

Check out more plants that are hardy in the South.

Zone 10

Zone 10 holds some of the hottest temperatures in the U.S., prevalent in tropical places like Southern California and Southern Florida. Plants in this zone can handle temperatures as low as 30 to 40 degrees.

When to plant: Mid January

Common plants:

  • Bougainvillea
  • Palmetto Palm Tree
  • Violet Churcu

Check out more plants that are hardy in Southern California.

Zone 11

Tropical plants flourish in Zone 11, which covers Hawaii. This zone holds year-round heat, and plants can withstand temperatures above 40 to 50 degrees F. There is no frost whatsoever, and native plants thrive throughout the whole year.

When to plant: Any time

Common plants:

  • Lime
  • Sago Palm
  • Grevillea

Download a Map of Your Area

Find your state from the list below to download a larger climate zone map that shows more detail of the gardening zones in your state. (Free, one-time registration required for members.)



















Maine Pennsylvania



USDA Plant Hardiness Zone Map

Even though you wouldn’t know it by looking outside Spring really is on the way. Which means many of us have started thinking and dreaming about our gardens.

As most people know, there are two baisc types of garen plants: annuals and perennials. Annuals live fast and die pretty. They last for only one growing season, and you have to replant them again next year. Perennials are the mainstays in the garden. They come back year after year. Many don’t hit their prime for two or three years, making year-round care of the plant important. One of the most important things to consider before purchasing a perennial for your garden is what its hardiness zone rating is, to know if it will survive the winter in your garden.

The US Dept. of Agriculture Plant Hardiness Zone Map is now the standard device used to label plants in the US.

It represents the average annual minimum temperatures in 11 zones which vary in ten-degree differences. Each main zone is further divided into two sections, A and B, based on 5-degree differences. The map is now interactive. You can enter your zip code or state and it will tell you which zone you are in. You can also click on a state on the map and a popup map will appear showing the zones as well as county lines, major cities and rivers.

A bit of history:

The earliest versions of national hardiness maps were developed in the 1920’s and 1930’s by a variety of groups, most notably the Arnold Arboretum at Harvard University. The first USDA Hardiness Zone map was published in 1960 and updated in 1965. Because it used a different temperature scale for its divisions than the Arnold Arboretum map, it often led to confusion for gardeners rather than clarity. The USDA map would not be updated again until 1990 when it underwent a huge overhaul, using data collected between 1974 and 1986. Additional zones were added to include Canada and Northern Mexico as well as Alaska and Hawaii. Th 1990 map standardized its division s into the well-known 10 and 5 degree division, and became the default hardiness zone map in the US.

There is one big drawback to the USDA Plant Hardiness Zone Map however, it deals with only the average minimum temperatures. It does not take into account summer weather at all. Heat, humidity and rainfall are also just as important to the survival of a garden plant, and all that information is found on plant tags as well. But where can you find maps that give you this information?

One of the best sources of this type of information is the PRISM Climate Group at Oregon State University. In fact, the USDA used much of their winter data in the most recent overhaul of the Hardiness Zone Map. From their web site: “The PRISM Climate Group gathers climate observations from a wide range of monitoring networks, applies sophisticated quality control measures, and develops spatial climate datasets to reveal short- and long-term climate patterns.”

“PRISMs homepage can be found here. From this page you can find lots of neat informational maps.

  • The link to 30 Year Normals takes you to a map that compiles the data from 1981-2010, and you can adjust it to see precipitation or temperature and you adjust by month.
  • The link to Gallery of State Maps takes you to a US map that you can then click on state by state to see the average annual precipitation (1981-2010) by state.

Combining information from The USDA Plant Hardiness Zone Map and the PRISM maps, can give you a lot of information about where you live and the types of plants the will probably work best in your area. Unless you are dealing with a microclimate. But that’s another topic for another blog post. Happy Gardening!

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