Fall colors are way more complicated than I ever knew. The truth about orange and yellow leaves is that those pigments are always present in the leaves. It’s in their DNA. However, during the spring and summer months they are so flooded with chlorophyll (which helps them convert sunlight into energy) they appear green. In other words, chlorophyll masks the true colors. Then in the fall, when the days are shorter and cooler (sigh), trees stop producing chlorophyll. That’s when the leaves’ true colors are revealed.
Red leaves are a different story. That pigment is not there throughout spring and summer. Instead, as sugars get trapped in the leaves as a result of the changing season, a chemical changes occur and produce the new red pigments (called anthocyanins for those wanting a new word today).
Another factor that affects leaf color and how long we get to enjoy the fall colors, is weather. The short version is that optimal weather produces optimal colors for a longer period of time. Picture your perfect fall day: warm and sunny, followed by a crisp, cool (but not freezing) night. That’s optimal. The reason is because low temperatures destroy chlorophyll, thus allowing leaves’ colors to shine. Bright sunshine also apparently breaks down chlorophyll. During the summer chlorophyll breaks down and is regenerated continuously in tree leaves. But in the fall, nights grow longer and chlorophyll production slows; eventually not enough chlorophyll is produced to replace that broken down by the sun, again allowing the color to come through.
The bottom line is that there are a variety of factors that effect leaf color. But, a warm and wet spring followed by moderate summer weather and then warm fall days and cool night, produce the most brilliant colors.