The beautiful natural phenomenon of reds, oranges, and yellows happens on deciduous trees every year, but not everyone understands why. That’s where Ben Heusinkvelt, orchard and grounds manager and certified arborist at Arbor Day Farm, comes in. Ben has taken the time to answer some questions that will help you understand the wonders of fall leaves.

Why do leaves change color in the fall?

During the growing season, leaves get their green color from photosynthesis-generating pigment called chlorophyll. In the fall, lower temperatures and shorter periods of daylight trigger a response from trees that winter is coming, and they need to prepare for dormancy. They stop making chlorophyll in the leaves, which allows the other pigments to shine.

What determines which color the leaves turn?

The color depends on which pigment is most present in the leaves after chlorophyll production has stopped. Red and purple colors come from pigments called anthocyanins, while carotenoids yield oranges and yellows. How much of each pigment, and therefore the color of the fall leaf, depends on the tree variety and its location.

Some years, the fall colors are better than others. Why is that?

The weather throughout the year and just leading up to fall plays a tremendous role in the fall colors. Sunlight, water, and temperature all determine the brightness of leaves as they change. This is because certain conditions allow for creation of more of the secondary pigments and a longer color change. Rainy, cool springs followed by mild summers and cold fall nights tend to be the best recipe for fall colors.