Growing zones help gardeners choose which plants can survive and thrive in their yards. Also called "planting zones," they essentially separate the United States into regions based ground hardiness. If you're ready to plant, get to know your plant zone.
What Are the Gardening Zones in the U.S.?
Do you need those gardening zones explained? Many plants adapt to various growing conditions, such as soil types, humidity differences, and water fluctuations. However, plants can only tolerate certain temperatures in the winter. That is why hardiness zones are so vital to your home garden.
If you plant a shrub, tree, or flower in a colder zone, it may not be able to handle those temperatures. Gardeners use these zones to select the right plant to survive the winter months. The United States and Canada comprise 13 growing zones.
Each zone differs from adjacent zones by 10 degrees F. All zones are divided into "a" and "b" segments, each representing 5 degrees of temperature.
There are five different regions in the United States, and they contain several hardiness zones. Here is a closer look at them.
This region starts at the northern border of the United States, ranging from Illinois to the western section of South Dakota. This North Central region covers hardiness zones 3 to 7, with winter low temperatures ranging from -40 to -15 degrees Fahrenheit.
The North East region extends from the East Coast west to Kentucky and Michigan and south from Maine to Virginia. Zones 3 to 8 are covered in this region. Like the North Central region, these winter lows range from -40 to -15 degrees Fahrenheit.
These hardiness zones include all of Wyoming and Montana, extending to the West Coast. The North West region has a wide range of hardiness zones, from 3 to 9. Winter lows average -40 to -10 degrees Fahrenheit.
The South Central region features four states: Texas, Arkansas, Louisiana, and Oklahoma. The hardiness zones range from 6 in the northern areas to 10 at the southern tip of the Lone Star State. Low temperatures in winter fall in the range of -10 to 15 degrees Fahrenheit.
Mississippi, Tennessee, and most of the Atlantic Southern states are included in the South East region. Hardiness zones 5 to 11 are part of this region, with winter lows ranging from -15 to 45 degrees Fahrenheit.
The last region is the South West. It covers Colorado and other states in the western and southern parts of the country. Like most areas, this hardiness region encompasses a wide range of zones: 3 to 11. The winter lows tend to range from -35 to 40 degrees Fahrenheit.
Who Defines Gardening Zones in the U.S.?
There are two hardiness maps for North America. One of them is produced by the U.S. Department of Agriculture (USDA) and the other by Natural Resources Canada (NRC). These governmental agencies use different measures to create their maps.
U.S. Plant Hardiness Zones Map
Now, here's a look at the Plant Hardiness Zones map for the United States.
Planting Zone 1
Zone 1 is the coldest in the United States. With winter temperatures as low as -60 to -50 degrees Fahrenheit, it can be challenging for gardening. All plants must withstand the harsh cold in this tundra climate. Annuals are popular choices since they don't need to survive the winter.
Planting Zone 2
Planting zone 2 features average winter lows between -50 and -40 degrees Fahrenheit. Drought conditions and high winds are found in these zones. However, some native plants and annuals can be successfully grown in this zone.
Planting Zone 3
You can find zone 3 throughout Alaska and the northern part of the United States. Extreme cold, low moisture, and high winds can affect the growing conditions. This zone sees average lows ranging from -40 to -30 degrees Fahrenheit. Many native plants can be grown, with a few flowering annuals and vegetables. Some gardeners extend the growing season by starting annuals and vegetables indoors.
Planting Zone 4
This zone covers those regions in the higher elevations of the western mountains, northern portions of the United States, and coastal areas of Alaska. These unique areas have average low temperatures between -30 to -20 degrees Fahrenheit. Gardeners experience fewer challenges than those in the colder zones. Still, the growing season is short, affecting the flower and vegetable bloom times.
Planting Zone 5
This zone includes portions of New England and the North Central region. This zone experiences a moderately cold winter, with average lows between -20 and -10 degrees Fahrenheit. The growing season is short, but it can be extended by using starter plants or cold frames in the garden. Any plant suitable for this zone should be considered a cold-hardy variety.
Planting Zone 6
Zone 6 covers a large portion of the country. It is known for its moderate climate, with winter lows ranging from -10 to zero degrees Fahrenheit. The winters are cold, but the mild-to-hot summers give you many growing options.
Planting Zone 7
Planting zone 7 covers 15 states. These regions have cool winters, with average lows falling between zero and 10 degrees Fahrenheit. Since the zone is large, gardeners must consider other factors for their plants, such as soil conditions. A few adjustments may be needed for a successful garden.
Planting Zone 8
Zone 8 is one of the warmer regions in the United States, with minimum winter temperatures between 10 and 20 degrees Fahrenheit. Gardeners can enjoy an extended planting season with the milder winters and hot summers.
Planting Zone 9
Gardeners can enjoy year-round planting in zone 9. States in this zone include Florida, Texas, Arizona, and California. This zone features hot summers and warm to cool winters. Average lows in winter range from 20 to 30 degrees Fahrenheit. Gardens remain active with thriving tropical plants throughout the year.
Planting Zone 10
Located in southern Florida, Hawaii, and southern California, the average minimum temperature in zone 10 is 30 to 40 degrees Fahrenheit. While gardens in these zones can avoid freezing temperatures most of the time, the high summer heat does limit the planting possibilities.
Planting Zone 11
Planting zone 11 is located in the Florida Keys, Puerto Rico, and Hawaii. This hot zone features mild winters with average lows ranging from 40 to 50 degrees Fahrenheit. Heat has a bigger impact on the garden than those winter temperatures.
Planting Zones 12 and 13
These zones are not found in the continental United States, but they are located in Puerto Rico and Hawaii. Zones 12 and 13 are known for tropical and warm environments. Plants suited for intense heat can be grown in these areas.
Extra Map: Plant Hardiness Zones in Canada
Canada also has its own plant hardiness zones, ranging from 0 to 9. British Columbia has the warmest areas, and the coldest regions are located in the northern territories. Like the USDA hardiness zones, the Canadian map helps gardeners choose the right plants to thrive and survive in their yards.
Now that you know the plant hardiness zones for your location, find a store near you to pick up plants, flowers, and shrubs for your garden.