What Are Plant Hardiness Zones?

Find Planting Zones for the U.S. and Canada

September 27, 2019
USDA Plant Hardiness Zones.png

Plant hardiness zones—also known as planting zones or growing zones—help gardeners understand which plants can survive their region’s climate. Find out which planting zone you’re located in and grow the best garden possible.

What are Planting Zones?

When choosing plants for your garden, it’s important to select varieties that can thrive year-round in your area, especially in regions where extreme winter temperatures are normal. Planting zones define, generally, which plants you can grow in your area, and zones are typically listed in plant growing guides for reference.

The two most commonly referenced hardiness zone maps are those produced by the U.S. Department of Agriculture and Natural Resources Canada. Different measures are used to create each country’s map, as is explained below.

Note: Zone maps are not absolute; if you find the information contradictory to your own experience, you may live in a microclimate. Soil, moisture, humidity, heat, wind, and other conditions also affect the viability of individual plants.

USDA Planting Zones Map

Considered the standard measure of plant hardiness, the USDA Plant Hardiness Zone Map is based on average annual minimum winter temperatures. The map is divided into thirteen distinct 10ºF zones, which are further divided into sub-zones of 5°F.

Check out the official USDA Plant Hardiness Zone Map below, then go to the USDA website to find out which zone you live in!

USDA Plant Hardiness Zones Map, 2012.
USDA Plant Hardiness Zones Map, 2012.

Click here to see the full USDA Plant Hardiness Zone Map.

Note: The USDA Plant Hardiness Zone Map was last updated in January of 2012, the first update since 1990. About half of the country was made a half-zone warmer on the map. According to the USDA, this is not a statement on global warming; rather, the scientists are using a different set of long range data and more sophisticated computers for a more accurate map, especially in challenging areas such as mountain zones, which may have been rated too cold or warm in prior iterations. Learn more about the updated map here.

NRC Canadian Planting Zones Map

Unlike the USDA map, which is based only on minimum winter temperatures, the planting zones map produced by Natural Resources Canada considers a wider range of climatic variables, including maximum temperatures and the length of the frost-free period. However, the NRC also produce a map that shows plant hardiness zones for Canada based on the USDA extreme minimum temperature approach. Click here to see both Canadian planting zone maps.

Check out a simplified version of the official Natural Resources Canada Plant Hardiness Zone Map below, then go to the Natural Resources Canada website to find out which zone you live in!

Natural Resources Canada Plant Hardiness Zones Map, 2014.
Natural Resources Canada Plant Hardiness Zones Map (simplified version), 2014.

Click here to see the full Natural Resources Canada Plant Hardiness Zones Map.

Planting Zone Tips

Flowers, shrubs, trees, and all plants grow best when planted in the appropriate zone. You’ll find that winter damage occurs most when plants are out of their range or “comfort zone.” When you choose plants for a garden or landscape, avoid selecting plants that are marginally hardy for your region; that’s when you’ll see winter damage, poor growth, and a reduction in flowering.

Planting native species is a surefire way to achieve a stable garden. See our article on natural landscaping.

Another key part of successful gardening is knowing when your frost dates are. Find your local frost dates here.

What are your thoughts on planting zones? Are they accurate? Let us know in the comments below!

Reader Comments

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Zone 9b

I am wondering if I am in zone 9b can I pick plants from 9b and lower like 7b? If it is only about the frost date. I was wondering if there was a zone map for Maximum heat? That would help me a lot. Every summer plants even for zone 9b get fried from the summer heat.

In the US there is also a

In the US there is also a heat zone map developed by the American Horticultural Society. Unfortunately I don't know if there's an equivalent map for Canada to figure out which zone you'd be in, but since I live very close to the border, I use the part of the map closest to my area. Lots of plants that do well in zone 7b will do well in zone 9b too, especially if the type is noted as being heat/drought tolerant. If you're growing vegetables, you can often look up the maximum and minimum temperatures that the plant needs at different life stages and compare it to the temperatures on your plot.

There are a few things I've done that have caused my plants to be stressed from heat. Planting at the wrong time of year (spring/fall crops like lettuce in summer), in the wrong spot (tender plants that need shelter out in the open) and underwatering are probably the big ones. Underwatering was most easily fixed for me by making sure everything was in deep soil or a very large pot (so that there's a large reservoir of water that can be drawn from) and using mulch over bare soil to reduce evaporation. Hope that helps!

Accuracy of zone map

According to the Canadian zone map I live in Zone 0A in Kuujjuaq, Quebec. According to the USA map I live in zone 2A. According to the Canadian map Kuujjuaq is in the same zone as all of the areas north of us such as Baffin Island NU. We are south of the tree line and we have quite a number of trees growing-Spruce, Larch, Quaking Aspen, pussy willows, Labrador tea, blueberries, etc. Having traveled up to various places in Nunavut, it is hard for me to believe there has not been a mistake made in developing the zone for our area. According to the Boreal forrest map, we are in it. Nunavut does not have any trees and much more tundra and barren land and they can barely grow crowberries and I don't think there are any blueberries at all. Since I am about to start gardening this coming summer which will include purchasing perennials 1,000 miles south of here I would like to know if our region has only been given a rough estimate of what zone it is. We are remote and are often mistakes are made for this area.
Even zone 1 would be ok as I have found some zone 1 peonies to purchase online. Thank you!

Accuracy of Planting Zone Designation in Question

I am concerned that my area, to which I am a relatively new resident, is not zoned accurately. The designation for my area – 9B — places me in a location subject to winter freeze; however, "first frost" occurred a full month earlier than indicated by the available information (this website indicates first frost occurs in mid November but in my experience it takes place in mid- late October). The lowest temp my area hit this past winter was 14 degrees (there were 2-3 nights where this was the case). While snow isn't a regular occurrence in/around the high desert, it is not uncommon to receive a smattering of snow each winter thanks to the elevation, which sits just above 3,000 feet. More than snow, however, a regular feature of where I live is wind — moderate to high winds that can add to the wind chill factor in winter and potentially damage a garden year-around.

1) How consistent is what I have described about my climate with Zone 9B designation?
2) Whom can I contact if I feel that the area has been incorrectly assessed? (I will be out the money for lot of plants I bought to start a garden this Spring if conditions do not, in fact, meet Zone 9 criteria.)
3) Given the reality of winter/summer temperature extremes, pervasive winds and sub-20 percent humidity levels, which are common to my desert foothill region, what should I be looking for with respect to landscaping apart from the "cold hardiness" or "drought resistance" indicated on the plant tags?

USDA Planting Zones

The zonal designations are solely based on the lowest average temperatures typically seen in that area. According to the USDA, this is 25°F for Zone 9b, but temperatures are certainly capable of dropping below that for short periods of time. Elevation is also a factor, as is wind. These things also affect the first and last frost dates—elevation especially. It’s likely that the nearest climate station (which is where the frost date is calculated from) is at a lower elevation than your garden, which is why the date is off so much.

It’s possible that your area has been mis-zoned; contact the USDA to inquire about their mapping process. Here is their contact information: USDA - Contact Us 

As for plants that would work for your garden, look into gardening with alpine plants—plants that naturally grow in high elevations and in environments with high winds and cold temps. Alpine plants typically grow low to the ground and have short, tough foliage to avoid being blown over by harsh winds. Low-growing sedums and other cold-hardy succulents (like hen and chicks) are good choices, as are ornamental grasses and coniferous plants like juniper. To help prevent wind damage, consider building berms or stone walls around your garden beds, and look into creating your own “rock garden.”

India zones

I did not see the map of india in zoneal maps. Will you please tell in which zone Kota, Rajasthan, India is and that what are the best plants to be grown in a highly hot area like this?

India Zone info

For India zones: check out the Koppen climate classification system. Also look for your latitude and distance from ocean in the USDA map to find your climate analogue. Something to keep in mind: each 1000 Meters above sea level will be equivalent to a 1 degree increase in latitude, however your day length will not change. Or Wiki your latitude and look for climate analogues there.

Small Flower Gardens for the novice

I am transplanting a Delphinium Guardian Blue to a large outdoor pot. How large of pot do I need, 2, 3 or 5 gallon?

pot size?

You want to move the plant to a pot that will give it room to grow—so it will have a couple of few inches around its base. Too big a pot and it will look out of scale.

Remember, too, that you don’t want the pot to be too big, and so too heavy, to pick up!

Beginner gardner

Hi I'm a beginner gardner and I live in yuma az my zone is 10a what flowers are the best for pots and raised garden beds?

You have an endless list of

You have an endless list of possibilities in your hardiness zone, but just to name a few– Bird of Paradise, Black-eyed Susan, African daisies, Hibiscus, Snapdragon, and Gardenia.

This zone map does not take

This zone map does not take microclimates such as Niagara Falls into consideration. If we were zone 5 we would not be able to grow the tender orchard and vine fruits that we do.

ZONE 7A Niagara orchards & vineyards

Please look more closely at the Natural Resources Canada map ➾ it shows that the regions of the Niagara Peninsula below the escarpment are, in fact, ZONE 7A ➾ not zone 5.

Click on the map or go to www

Click on the map or go to www.planthardiness.gc.ca/?m=1 to see a larger PDF of this map and the different colors around Niagara Falls.

Visit your local county

Visit your local county extension agent office to obtain exact hardiness zone data plus list of plants that thrive in this zone.

You can also contact your state agricultural college for updated info on
state wide hardiness zones.

If there is a master-gardener program in your area get a list of master gardeners and contact one or two of them.

Thanks for sharing and

Thanks for sharing and explaining the change. It’s interesting to see how the zone can shift just 10 miles away.

If I look at the hardiness

If I look at the hardiness Zone map it looks like I'am in zone 7 (light green)on the farmers almanac map. But when I type in my zipcode for farmers almanac it says I am zone 5. Which in my mind is a big difference so How am I to know which zone to go by. Thanks


The Editors's picture

Hi Edna, First click on the picture of the USDA map. Then, it will take you to the USDA web site. On that site, you can enter your zip code. Here is the direct link to the USDA web site: http://planthardiness.ars.usda...
I hope this helps. --TOFA