Most foliage damage to these plants occurs when they are actively growing and are very tender a few days prior to a temperature drop. This is when the plant cells are most sensitive to freezing.
Cold injury to plants in somewhat confusing. Winter injury is a term that is used to cover the gamut from fall, winter and spring damage to plants caused by a variety of reasons.
It is also very difficult to really determine what actually caused the injury. For instance, if we have an extremely dry summer, fall and winter, plants may dry out due to lack of water and not cold temperatures.
Sometimes winter damage doesn’t even show up for a couple of years, making it even harder to diagnose.
I remember the year after the 1988 drought. I was working in a garden center, and for some reason we had numerous customers come into the store complaining of dead crabapple trees in June. These were trees that were anywhere from newly planted on up to mature.
We ruled out all other types of damage and believed that it was due to the drought from the previous year. The plants had enough reserves to leaf out in the spring. However, when the heat of summer hit, they didn’t have enough of a root system to support the plant.
Low temperature injury occurs when plants are exposed to temperatures lower than they tolerate. This can be avoided by using plants that are recommended for your USDA Plant Hardiness Zone. You can find the map by doing an online search for that term.
Our plant zone in the Miami Valley is 6a. Plants that are listed in zones with higher numbers might not survive our winters.
I used the words “might not survive.” As gardeners, we tend to push the envelope and try to get some of those plants that are listed for further south to grow in our gardens.
And sometimes we succeed. This is usually due to microclimates that we create in our landscape to protect the plants. It’s also possibly due to the fact that the temperatures never drop low enough to cause failure.
The hardiness zone is a recommendation in order to understand which plants will thrive in your location. Keep in mind that plants are affected by a lot of environmental factors; therefore, we don’t always know what might cause plant injury.
About the Author