The USDA plant hardiness zones have changed a bit over the last few years. These zones outline different regions of the country to help plant owners decide which flowers, trees, shrubs, and other plant life they can successfully grow in their zones. With the latest 2023 revision, zones that were considered too cold for certain plants are now a bit more friendly, allowing plant owners a bit more flexibility when choosing their newest landscapes and garden features. Landscape contractor Jenn Nawada explains it to host Kevin O’Connor.
What is the USDA Plant Hardiness Map?
The USDA Plant Hardiness Zone Map divides the United States into zones that indicate the lowest likely temperatures to reach those regions during the winter. The zones reflected on the 2023 revised map are the result of more data compiled by experts using 30 years’ worth of information. The changes took into consideration the lowest temperature each year over that 30-year span and coordinated with the zones provided on plant labels and information.
The goal is to help DIYers and pros choose plants that are most likely to survive during the winter due to exposure from temperatures that are lower than they can naturally withstand.
Revised Map Reflects 30 Years of Data
The 2023 version of the map reflects the mean annual extreme minimum temperature across the span of 30 years. The current map was developed using data recorded from 1991 to 2021. The coldest temperatures reached each year were averaged and the zones were developed accordingly, as those average low temperatures are higher than they used to be.
Options are Changing
Depending on where you are, your hardiness zone might have changed. Over time, many zones have gotten warmer, meaning that these zones are more accepting of a wider range of plants. For example, the Boston area was always Zone 5 but has progressively warmed to 6a and 6b, with some areas around the coast even being Zone 7a. Now people in the area can choose plants based on these new zones.
Not Everywhere Changed
There are a lot of areas where the temperature didn’t increase or stay consistent. Some areas didn’t have to change based on their 30-year average. To find out if your planting zone has changed, head to the USDA website and punch in your zip code. This will tell you what your current hardiness zone is so you can choose the right plants based on the latest information.
So, What’s Next?
The USDA Plant Hardiness Zones are only concerned with the coldest temperatures. This means that the zone changes don’t impact vegetable gardens, lawns, or established plants. It’s simply a way to hedge your bets against plants dying over the winter by choosing plants that can withstand the winters in your local area.
Resources
The 2023 USDA Hardiness Zone Map
Expert assistance with this project was provided by the United States Department of Agriculture.