Fall Color: How Leaves Change Color in Fall

The brilliant fall color in our landscapes is a magical transformation that happens each year. And the science behind it all is just as intriguing.

Each Fall as the days shorten our deciduous trees and shrubs begin this transformation. The plants produce less of the chlorophyll that gives leaves their normal green color. In fact, the chlorophyll starts breaking down revealing the underlying pigments of yellow, red or orange.

At the same time these plants begin to create an abscission layer between the leaf and stem. This barrier prevents the sugars produced in the leaves from moving down into the roots for storage. Warm sunny days followed by cool nights without a hard frost mean more sugar and better red, orange, and purple fall color.

Genetics determine the color each plant tends to produce in fall, while weather and the plant’s health influence if and how intensely the color will be expressed.

A bit more information: Avoid excess nitrogen fertilization and keep your trees and shrubs properly watered and mulched to get the best possible fall color in your landscape. Include plants suited to your growing conditions with the fall colors you prefer. Birches, ginkgo, lindens, and witchhazels are a few plants programmed for yellow fall color. Sumac, red maple, and American viburnum have red leaves in fall while the tannins in oak leaves give many of them a deep brown fall color.