Why Leaves Change Color in the Fall

Near downtown San Diego, we don't see much change when it comes to vibrant green leaves naturally transitioning to hues of deep yellow, orange, red, purple, and brown. A short drive east, however, allows us to truly experience the breathtaking beauty of a large landscape amid this transition of dipping temperatures and fewer hours of sunlight.

So, why do leaves change color from vibrant green to fiery autumn hues? It starts with green-pigmented chlorophyll, which is concentrated within plant cell walls. Chlorophyll absorbs sunlight and initiates photosynthesis, nature's process of taking light from the sun and converting it into glucose (food) for a plant.

In many trees and shrubs, chlorophyll requires a certain amount of sunlight daily to do its job. So as days shorten, the chlorophyll begins to break down, and the green pigment begins to fade.

What comes next is the cool part. The leaves of hue-changing trees, such as Maples, Aspens, Oaks, and so many more, contain a rainbow of additional pigments within their leaves. These other hues, however, are often masked by the vibrant green coloring of chlorophyll. As the concentration of chlorophyll decreases, the normally hidden fiery colors get their opportunity to shine.

I've included an Autumn Leaves lesson in our Rutabaga Education Curriculum Fall books. Click here to learn about teaching this "nature magic" to elementary-aged children, along with various age-appropriate fun autumn leaf activities to bring the learning to life!

You can also watch this Autumn Leaves Video to preview lesson content!