The Newly Revised USDA Plant Hardiness Zone Map

Frequently Asked Questions

What is the difference between an annual and perennial?

An annual is a flower or vegetable with one life cycle, usually spring through fall.  An annual does not grow back year after year. It “dies” every year, but reproduces itself in the form of seeds. Therefore, it does not have a USDA Plant Hardiness Zone recommendation. However, if winters shorten in length as a result of the warming trend that the USDA has observed, annuals will have a longer life cycle.

Perennials, as well as trees, shrubs and some fruit plants, grow back from winter year after year.  These plants have a USDA Plant Hardiness Zone recommendation meaning that they are hardy only to a certain temperature.  A plant with a cold hardiness to zone 6, for example, most likely will not survive the winter and grow back in the spring if it is grown in zone 5. 

What is the Purpose of the USDA Plant Hardiness Zone Map?

The USDA Plant Hardiness Zone Map identifies your garden’s hardiness zone. It measures “average minimum temperature”—with the key word being “average”. Therefore, a brief and freak cold snap will not affect the zone designation, because it doesn’t kill most plants. So, it is the level of coldness over time that is most significant, since that is what kills plants, along with wind.

The map is helpful to gardeners who want to know which perennials, trees, shrubs and some fruit plants are hardy enough to grow successfully in their garden. The USDA Plant Hardiness Zone Map does not impact annual flowers and vegetables because these plants only have one life cycle during spring, summer and fall.

What kind of flowers and vegetables are impacted by the new USDA Plant Hardiness Zone Map ?

In general, only perennials, trees and shrubs have a recommended Plant Hardiness Zone.  Annuals, such as petunias, zinnias and marigolds, do not have a USDA hardiness zone recommendation.  Most vegetables are considered annuals and are not impacted by the new USDA hardiness zone map.  Remember, hardiness measures the hardiness of plants that overwinter, not plants that are annuals.

I’d like to buy perennial seeds from Burpee. How can I be sure that the variety I purchase is appropriate for my hardiness zone?

Perennial items on the Burpee website, in the catalog and at retail stores are clearly marked with hardiness zone recommendations. To ensure that your purchase is appropriate for your zone, you should refer to the USDA Plant Hardiness Zone Map to determine the zone recommendation for your locale. To make shopping for “zone appropriate” plants even easier, you can personalize your plant search on the website by adding your zip code to the “Personalize Your Site” section on the top left hand corner of our homepage.

I purchased or plan to purchase your seeds this year.  Is the hardiness zone map on the back of the seed pack outdated?

A zone map is only featured on Burpee’s perennial seed packets and is a condensed version of the USDA Plant Hardiness Zone map. Since the recent changes to USDA Plant Hardiness Zone Map were very minimal, the zone maps on the back of Burpee’s perennial seed packs are still accurate.

I still have questions about my zone and the newly revised Plant Hardiness Zone Map. Where can I find answers to these questions?

Gardeners with questions about their zone, the revised map or general gardening questions are welcome to call our customer service department at 1 (800) 888-1447. We also encourage customers to visit our “Burpee’s Backyard” community site and our “Burpee Ask and Answer” page.

*Note: Please note that Burpee is still working to update its plant hardiness zone maps to the most recent version released by the USDA for both operations and for regional news and recommendations. 


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