Oct 11, 2023 3 min read

Are you getting a chance to take in the fall foliage this week? It might be a great time to do it, with temperatures recovering a bit from the chilly weekend and also forecast to drop again this coming weekend. Combine that with a chance of late-week rain and our leaf-peeping opportunities might become a bit more limited after that.

Prime color change for Washington, Greene and Allegheny Counties is mid to late October, with the Laurel Highlands already seeing near peak color and peak shades of red and golds already popping in areas up closer to Lake Erie.

One tree in our yard switched half its leaves from green to crimson two weeks ago seemingly overnight. After wind and a bit of rain last weekend, the reds were all knocked off and now it’s half empty and half green.

Do you know why leaves change color? They appear green in spring and summer because they’re filled with chlorophyll, which trees use for photosynthesis – the chemical reaction that turns sunlight into sugars for food. As weather cools and the days grow shorter, trees’ chlorophyll breaks down, leaving other chemicals that cause color change. That unmasks xanthophyll to produce yellows, carotenes creating oranges and anthocyanins giving us reds.

The weather does affect those colors, making them brighter when late summer is dry, and autumn has sunny days and cool nights. But why do some trees go through all of this rather than just keeping their leaves all year round? The answer is that they want to get rid of their leaves so they don’t have to worry about repairing them if they would freeze. If that would happen, it would cause tissue damage and that means the tree would have to expend even more energy to repair that tissue damage. The alternative? Shed the leaves before they have the chance to freeze and just grow new ones when it’s time for spring sunshine.

Here’s a fun and easy home experiment for the kids that reveals leaves’ hidden colors: Mash up a bunch of green leaves from a tree and soak them in acetone (better known as nail polish remover) or rubbing alcohol overnight. You can try a few different trees each in their own cup or bowl. The next morning, dip a strip of paper towel into the liquid solution for a few minutes, then hang it on the inside of the bowl or cup. Let it sit for about half an hour. When it dries, you’ll see bands of color pigments including the green but also some of each leaf’s true hues.

Enjoy the fall color show while it lasts. Pretty soon, it’ll be time to grab the rake!

Kristin Emery can be reached at kristinemery1@yahoo.com.