Newly-Released USDA Zones Map
 
Hold onto your hats, folks. This week's installment of The Plug® provides the North Creek Notes on the recently revised USDA hardiness zone map. The last update was published in 2012—needless to say, there’s been considerable and meaningful chatter about the new map designations—here are the facts:
 

Is it Getting Hot in Here?

• Half of the United States has shifted up one half-zone and half of the United States is in the same zone. Check the map to see if your area has changed with the new update: https://planthardiness.ars.usda.gov/.
• Updated map is more precise than previous maps because of the collaboration of the USDA with their PRISM Climate Group at Oregon State University utilizing highly detailed GIS datasets.
• Incorporates double the data - 13,412 weather stations used in 2023 compared to the 7,983 used for the 2012 map.
• Precision with GIS mapping allows for zone designation that considers heat island effect in cities versus surrounding countryside or a finer degree of accuracy for lake effect or mountain altitude differences. Gardeners in these areas will appreciate the more accurate resolution detail.
• Zones are broken down into A and B subzones for greater detail. Zones are based on 0-10 degree difference, with lower zones having lower minimum degrees during winter. Subzones are broken down into 0-5 degree differences. This detail allows greater accuracy in the map.
• Two new zones added for Puerto Rico and Hawaii - Zones 12 and 13 have been introduced for regions with average annual extreme minimum temperatures above 50 degrees and 60 degrees F, respectively. This is also useful for people wanting to know the hardiness for tropical or subtropical plants and their cold sensitivity.
• Map changes of zones in an area do not necessarily result from climate change. The increased accuracy and data set means that part of the changes are due to having more information available and being able to map it more precisely. USDA Hardiness zone map takes into account extreme averages over thirty years. In contrast, climate change data models are based on average temperature changes over 50-100 years, so changes in USDA hardiness zone may not reflect climate warming since they use different data averages and timelines.
• Canada’s hardiness zone map: http://planthardiness.gc.ca/

Learn more about the new map from the USDA:
 
USDA Unveils Updated Plant Hardiness Zone Map
 
Information About How the Map Was Created
 
North Creek is zone 7a - what’s your zone? Has your zone changed? Did the updated map reaffirm what you already noticed for your area? Let’s talk about it! Join the convo on Instagram and Facebook!