Why Leaves Change Color

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: Examine any trees and shrubs that exhibit early fall color. This can be an outward signal that the plant is suffering from girdling roots, stem rot from deep planting, disease or severe drought. Contact a certified arborist for help diagnosing the cause and developing a plan of action.