Written by: Certified Arborist, Jean Ferdinandsen
In many northern parts of the United States, fall color in trees is something to look forward to by nature lovers. Will it be a good color year, where, when…? Why does this happen, and is it a good thing?
As temperatures dip, many leaves change color, then fall off. This is an energy saver for the tree. It’s hard to sustain leaves when temperatures are low, water is unavailable, and there is less sunlight during the winter months. To prepare for dormancy, nutrients and carbohydrates are transported into the root system for storage.
Varying pigments in leaves account for the color. Chlorophyll is the main pigment during the growing season that causes leaves to be green and photosynthesizes light to produce the sugars and carbohydrates that the tree needs to live.
With colder temperatures and shorter days, chlorophyll production stops. This pigment is then broken down and reabsorbed into the tree. Other pigments are now revealed, allowing other colors to show.
Other leaf pigments include carotenoids (producing yellow to orange color) and xanthophylls (yellow). Anthocyanins are produced more in fall to cause red, pink, or purple colors. Fall color will vary depending on the amount of residual chlorophyll in the leaves and levels of other pigments.
The exact color that results have many variables and may not always be consistent from year to year, or from tree to tree. Temperature, light, and water supply influence the degree & duration of fall color. Low evening temperatures above freezing plus bright sunny days favor the development of good color. Drought or early frost can make leaves fall early, before having a chance to change color. Tree species /variety, soil type, site location, and age can all affect the color as well.
Adding trees to your landscape for fall color creates another layer of interest in the vegetative palette of your yard. There are many to consider that include (but are not limited to) : maple; buckeye; serviceberry; katsura; dogwood; larch; and bald cypress.
If you’d like help making sure the color on your tree is healthy or selecting something to add that splash of interest, call your Wachtel Tree Science Certified Arborist to guide you.