What Are Grow Zones and How to Find Yours

What is a grow zone?

Most every online nursery will list recommended ‘Grow Zones’ for plants they sell. Most nurseries will also void any warranty if you purchase plants outside their recommended grow zones. But what exactly is a grow zone?

The USDA Agricultural Research Service created the Hardiness Grow Zone Map. Hardiness is a reference to cold hardiness meaning how cold the average annual temperature is for that zone.

USDA Hardiness Zone MapThere are 11 hardiness grow zones that you will sometimes see broken up into ‘a’ and ‘b’ subcategories. The lower the number, the lower temperatures get.  Zone one is the coldest, zone 11 has the warmest winters. Each zone is separated by their average annual lowest winter temperature, broken down by 10-degree increments.

The USDA recommendation is to use your grow zone as a guideline to help determine which plants are most likely to thrive at your location.

There is an interactive grow zone map provided by the USDA that you can go to here. Simply enter your zip code and it will provide your grow zone. We have also posted hardiness zone maps for every state that you can view here.

What They Don’t Tell You

In general, humidity, sun exposure, winter protection and summer heat are not factored into a grow zone. Neither is soil condition, a critical factor in the ongoing health of any tree and shrub. Here’s an example; The grow zone for portions of the snow belt along Lake Erie have the same grow zone as parts of central Texas. Chances are you wouldn’t be looking for the same trees or shrubs for both areas.

So as the USDA states, use your grow zone as a guideline but take into consideration other factors. If you are not familiar with a plant you want to buy online and you’re not sure if it will do well, use the Grow Zone Hardiness Map as the first place to start.

There Are Always Exceptions

Let’s say you really want a plant, but you are 1 zone outside the recommended zones. Should you not buy it? As with almost everything in the plant world, there are always exceptions. Take into consideration all the other factors to help you decide. Just understand the consequences. Your plant may not survive, and the nursery will most likely void any refund and/or warranty.

Even though there’s a lot to consider ensuring your plants thrive, knowing if they will make it through your coldest winter weather should always be considered.

Find Your Grow Zone