Our Garden's Hardiness Zone Change

The USDA (United States Department of Agriculture) created a map that splits the country into 13 zones. Each zone represents a different kind of climate or weather pattern. The map is based on the average lowest winter temperature over 30 years. The zones are numbered from 1 to 13. Zone 1 is the coldest, where temperatures can go down to minus 50 degrees Fahrenheit (-45.6°C), and Zone 13 is the warmest, where the temperature rarely goes below 60 degrees Fahrenheit (15.6°C). In addition to the main zones numbered from 1 to 13, the USDA Hardiness Zone Map also includes 'A' and 'B' subdivisions within each zone. These divisions represent a slightly more detailed breakdown of climates. Each zone represents a range of average annual minimum winter temperatures of 10 degrees Fahrenheit. For example, Zone 7 ranges between 0 to 10 degrees Fahrenheit. But that's still a pretty big range! So, the USDA decided to split each zone into two parts: 'A' and 'B,' each representing a 5-degree Fahrenheit difference to make it more precise. For instance, if you're in Zone 7: Zone 7a would have winter low temperatures between 0 to 5 degrees Fahrenheit. Zone 7b would have winter low temperatures between 5 to 10 degrees Fahrenheit. These subzones 'A' and 'B' allow gardeners to choose plants more likely to thrive in their specific climate. These sub zones allow Growers to pick crop variety selections that may do a little bit better between those two cold zones.

So, if you live in Zone 3, you'll want to find plants that can handle cold winters. But if you live in Zone 10, you'll look for plants that can handle hot weather.

 

(For more information, go to this video: https://youtu.be/wzEtSCHDF0I?si=9wlgfCPN0t6oyLuc

 

Many of the growing zones have changed at least a half step since the 2012 determination. This might have something to do with climactic changes, but also due to the fact that  the last time the map was updated was 2012 and this was gathered from data from 7,983 weather stations the 2023 map was made from data from 13,4112 weather stations that's 5,429 more weather stations spread out, or almost twice as many. Other big change is in 2012 the map had a resolution of 6 and 1/4 miles in 2023 the resolution has been dialed down to just a quarter of a mile and you can you can see in this example that in areas that have converging growing zones. Also, keep in mind that it's the average annual extreme minimum temperature not the highest that it has ever been not the lowest temperature recorded in those areas each one of the zones is divide into a and b categories and the difference between the two is 5°. 

So, for our garden, we have shifted from zone 7a to 7b.