When can we expect the peak fall colors on our foliage?

BOWLING GREEN, Ky. – As of Monday, fall is officially here and we have already experienced many changes.

Cooler temperatures and wetter weather have all welcomed changes from the hot, dry summer that we’ve seen this year. But these changes can also have a negative effect, especially on our trees in the community.

From the extreme floods in the spring to the drought in the summer, these drastic changes can and have taken a toll on the health of our trees.

“The extreme rains that we had in the spring, they cause trees to grow a lot of roots,” said Jared Weaver, an arborist for the city of Bowling Green. “Often at the surface of the soil, which creates the problem when it dries up later on in the summer, like it has this year. That creates, a drought condition, which a lot of those finer roots that grew in the spring will die off. And it’s stressful for the trees to have such extreme shifts between, you know, wet and dry like that. And that can have a negative impact on trees. We’re seeing some trees that are ten, 20 years old now are being negatively impacted. They’re drying up. The leaves are turning brown. Some of them will recover over the winter. And some of them, the conifers particularly, we’re removing because they’re completely dead.”

But now that fall has set in many are anxiously waiting for the leaves to change color. And while weather does have an impact on those changing colors, an external factor plays a much larger role when it comes to determining when those leaves will be changing their colors.

“The thing that has the most impact is the daylight. The length of our days. So we’re going to have fall color regardless one way or another. But now that we’re getting a little bit of rain in the these first few days of fall, that’s going to help brighten up those leaves, make them have a little bit more that visual pop that we like to see. So hopefully we’ll continue to get a little bit more rain. When we have nice warm days and cooler nights. That really helps. The fall colors pop a bit.” Weaver said.

But why do the leaves change their colors? And what determines which trees will show? What colors?

“The color that a tree becomes in the fall is determined by the anthocyanins and other chemical compounds within the tree,” Weaver explains. “Certain species produce more of one chemical compound than in others. Like maples, they produce a lot of the reds and oranges and yellows. Oaks tend to be reddish or sometimes just brown. So it depends on the species of tree and what they produce and all those different chemical compounds. And then the fall when, when the day length changes, the trees slow down their production of chlorophyll, which is the green pigment. And, when they don’t produce any more chlorophyll than what’s existing in the tree breaks down, it lets those other colors pop and come to the forefront.”

So when should we expect the peak colors? Well for us here in south central Kentucky we can expect to see the most color on the tree starting in late October and early November. But make sure to enjoy it while it lasts, because the full color won’t be sticking around for very long.