Hardiness Zones: What and Where Are They?

Canada Hardiness Zone Map

Do you ever wonder why some plants thrive in your area while others struggle to survive? Understanding North American hardiness zones is key to selecting the right plants for your garden. In this blog post, we’ll give you an overview of these important zones and how they can help guide your gardening decisions. Whether you’re a seasoned green thumb or just starting out, read on to learn more about hardiness zones and how they impact plant growth across the continent!

Introduction to North American Hardiness Zones

In North America, hardiness zones are defined as geographical areas that indicate which plants are most likely to thrive in given conditions. The hardiness zone map of North America is divided into 11 zones, each of which is further divided into subzones.

The lowest temperatures recorded in each zone and subzone are used to determine the boundaries between hardiness zones. For example, Zone 5a has an average minimum temperature of -20 to -15 degrees Fahrenheit (-28°C to -26°C), while Zone 5b has an average minimum temperature of -15 to -10 degrees Fahrenheit (-26°C to -23°C).

Plants are categorized as either annuals or perennials. Annuals are plants that live for one growing season and then die, while perennials are plants that live for two or more growing seasons.

Annuals can become perennials in different zones and vice-versa. For example, Petunias are often treated as annuals in most hardiness zones, however, they act as tender perennials in Zones 9 to 11.

When choosing plants for your garden, it is important to consider the hardiness zone in which you live. This will help ensure that the plants you choose will be able to withstand the conditions in your area and that you are not replacing them each year.

Benefits of Knowing Your Hardiness Zone

Knowing your hardiness zone can help you take advantage of regional planting schedules. For example, if you live in Zone 7, you can plant delicate flowers such as impatiens and petunias earlier in the season than someone who lives in a colder climate.

Ultimately, understanding your hardiness zone is a helpful tool for both novice and experienced gardeners alike. By choosing plants that are appropriate for your area, you can create a beautiful and low-maintenance garden that will thrive for years to come.

Hardiness Zones Maps

Depending on what plants you want to grow, you will need to research which zone your region falls under, and then research which of your favorite plants are sustainable in your zone. Below are the hardiness zone maps for both Canada and the USA.

Canada Hardiness Zone Map
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USDA Hardiness Zone Map
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Plant Tag
Note the Hardiness Zones that are listed on the plant tag.

Once you know your zone, it is best to find plants directly in that zone or one zone cooler. For example, if you live in zone 5b – pick plants that will grow in zones 4 and 5. This way, should you have any unusually cold winters, you can assure you’re plants will survive. Looking at the tag shown here, this Rose Mallow Hibiscus is great for USDA Zones 5 to 9.  If you live in zones 4 or 10, you should not expect this plant to act as a perennial, nor can you expect it to thrive if planted outside of the required hardiness zones.


North American hardiness zones are a necessary tool for gardeners and landscapers when it comes to selecting the right plants for their gardens. By understanding these zones, you can choose the best plants for your specific area and ensure that they will be able to survive in the local environment. With this knowledge in hand, you can create beautiful gardens or landscapes that will stand the test of time and weather conditions, allowing you to enjoy them all season long

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