Learn about Hardiness Zones & Climate
One of the very first things you learn as a gardener is where you garden dictates almost every garden decision you make, from what kind of plants to plant, when to plant, and what your soil is like. After all, gardening in desert-like Arizona is quite a bit different than, say, tropical Florida or chilly New Hampshire. And it’s exactly this reason why the plant hardiness zones and your regional climate is so important!
When you're shopping for plants you’ll always see references to "Zones," which indicates the USDA Hardiness Zone. Sometimes you'll see references to climate, as well, so we want to be sure you understand how to identify your growing zone and climate so that you can pick out the best plants for your garden.
USDA Hardiness Zones
USDA Hardiness Zones are indicated on a map of the U.S. developed by the United States Department of Agriculture, based upon average minimum winter temperatures. The map is divided into 11 different zones, with each zone 10 degrees warmer (or colder) than the adjacent zone.
Why is this important? If you plant an agave, you want to ensure it won’t be wiped out by your area’s -30° cold snap (because sorry to say, it will be). That doesn't mean that you can’t grow agaves if you live in Minnesota, but you’ll want to be sure they’re planted in pots that can be moved indoors and protected during the winter.
When you’re reading up on plants or walking around the garden center, you’ll see that every plant has a tag or a label with growing information on it, including that plant’s hardiness zone. If the tag says, “Hardy to Zone 10” or simply “Zone 10,” you’ll know that the plant will be okay down to about 30°F.
So what is my zone? First, you get a gold star because you’re being a smart and informed gardener. Second, click this link to view the USDA’s interactive map. You can enter your zip code and see exactly what your particular hardiness zone is — but to get an even fuller picture of weather-related info to help you garden, keep reading.
Climate is related to, but different from, weather. Weather is what you hear about on the news every day — a report on the day’s temperature, humidity, rainfall, or cloudiness. Climate, on the other hand, measures the weather in a particular place over many years (Austin, Texas, for example), reliably letting you know what it’s like to live (and garden) in that place.
To use the Austin example, the climate in this central Texas city is mild in the winter, hot and dry in the summer (August is a beast), with periods of drought broken up by rain events. Spring tends to be the rainiest season, with fall a close second. The air tends to be more humid in the summer — no surprise there, as Austin is classified as a humid subtropical climate, meaning even straight hair looks a bit frightening most days.
So, if the Hardiness Zone tells you all about your average minimum winter temperatures, your climate gives you a slightly bigger picture. Believe it or not, our example city of Austin is in the exact same Hardiness Zone (8b) as Seattle is — but Seattle’s climate is very different from Austin’s, leading gardeners in both places to make very different gardening decisions and plant choices.
All of this information is valuable for you, as a gardener, to make the best choices for your garden that you possibly can. And while you might be disappointed to learn that you can’t grow hydrangeas very well in your desert garden, the entire cactus world is about to open up to you, my friend.
- Katie Elzer-Peters