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There is an updated USDA map of plant hardiness zones released in November 2023.
I recently wrote about why knowing your plant hardiness zone is an important first step to gardening.
In that article, I mentioned that the map was based on weather data from 1976-2005 and was subject to change.
The USDA decided that the time for change was November 2023, over a decade after the last map update in 2012.
Prior to the 2012 map that gardeners had been using, the previous map was shared in 1990 from weather data from 1974–1986.
For those keeping score, the 1990 map was based on 13 years of weather data, the 2012 map was based on 30 years of data and this new 2023 map is based on 30 years of data (1991-2020).
Not only will maps moving forward take longer stretches of time into account, this iteration accounts for nominal changes in temperature in dense industrialized cities versus rural areas and the elevation of the area.
All this to say, you should check your plant hardiness zone with your zip code.
Do not assume that you and a gardener you might follow on social media have the same zone because you live in the same state.
Did Everyone’s Plant Hardiness Zone Change?
The short answer is no.
This is in part because not all parts of the US are subject to extreme weather events that may skew the data from year to year.
For the regions that did see a change, including mine, it is partly due to the improved mapping techniques are more granular than in previous iterations of the map.
My Zone Changed, Can I Go Buy Plants For My New Zone?
Using myself as an example, I went from Zone 7b with an average minimum temperature of 5° to 10°F, to Zone 8a with an average minimum temperature of 10° to 15°F.
This does not mean I will never experience a winter temperature below 10°F. It only means anything below that is less likely.
I wrote in another article about how I came across a Mexican Bush Sage but I decided not to purchase it because it is only a perennial in Zones 8 and above.
Related: A Girl Walks Into A Nursery & Discovers a New Sage
With the updated map, I can now go purchase that plant with confidence that it is a perennial in my zone.
But WAIT A MINUTE…
If it is predicted to get below 10°F on a December evening in North Alabama, I still have to protect the plant.
The difference now is I can plant the Mexican Bush Sage in the ground and protect it on the few occasions that the temperature gets below 10°F.
The realistic option available to me prior to the zone update was to plant the Mexican Bush Sage in a container and bring it inside in the winter.
Honest truth: carrying a plant in and out of my home is not high on my priority list and that plant would have died.
I can, however, throw a cloth over my sensitive plants if the weatherman warns me inclement weather is likely.
Did your zone change? Does it limit plants you can buy or increase your options? Share below!