Reshaping Plant Hardiness Zones

Watkinsville, GA |

It’s no secret that weather is the driving force when determining what farmers can grow and when that seed should be put into the ground. That’s why the Plant Hardiness Zone map, which was recently updated by USDA, is such a valuable tool, as it shows the minimum temperature on any given day throughout the year.

“The zones are basically ten-degree averages in the temperatures. So, the colder ones that start with one and two in Georgia, really here we’re going from about seven to about nine across most of the state. Each of the zones is divided in half. So, there’s eight B, which is a little bit warmer and eight A because it’s closer to nine,” says Pam Knox, Agricultural Climatologist with the University of Georgia.

That new data shows some interesting results, as temperatures around the state and southeast have consistently been on an upward trajectory over the past thirty years.

“As time has gone on, what we’ve seen, and with this new map as well is that the zones are creeping to the north. As temperatures get warmer, what used to be eight A is now eight B. What used to be eight B might be a nine. So, that means that temperatures are increasing by say, four to five degrees Fahrenheit over time,” says Knox.

That is sure to have an impact on a number of crops, especially those that need lower temperatures in order to thrive.

“One of the things about peaches and apples is that they require cold weather in the Winter to grow; to be able to blossom in the Spring and so on. So, some of the varieties that used to work are not going to work very well because they are not going to get enough cold weather in the Winter. Farmers know this. They’re diversifying by planting in varieties that require fewer chill hours,” says Knox.

It’s not just the varieties that will need to be adapted, but also some different practices and timing when planting season rolls around.

“For something like corn, which doesn’t like hot weather very well, one adaptation strategy might be planting a little earlier in the year. You know, because the soil’s going to warm up as well under these warmer temperatures. So, that gives them the opportunity of getting that corn in a little bit earlier and giving them a little bit more time later in the growing season to maybe put in a second crop, some are double cropping,” says Knox.

This warmer climate could open the door for even more growing options for farmers in the future.

“Olives is another crop that are starting to be grown in Georgia. Who would have ever expected Georgia because we are so humid? They have to manage it a little bit differently but olives are something that’s being grown. In fact, this year, for the first time I believe, there’s commercial Georgia olive oil on some of the shelves in some of the specialty shops,” says Knox.

As for why this new study can be valuable for growers on both a large and small scale…

“Weather is, of course, one of the biggest driving factors of agriculture. So, they need to know what to expect because that’s going to determine even what kind of seeds that they buy before they even put anything in the ground, but it’s also going to determine how much money they can make. Farming is a business and so they have to be able to make money,” says Knox.

By: Damon Jones