Fall color can sometimes seem sporadic and inconsistent; in reality there are many controlling factors that result in a great or lackluster fall show. Autumn begins for plants when the days become shorter and the nights become longer. This single factor sets off the chain of events that results in fall coloring. Day length, soil moisture, temperature, and sunlight all play a role in the length and vibrancy of color we see. Chlorophyll, the leaf part responsible for the green color we see, starts to break down with these shorter days. Warm days with lots of sunshine and cool nights cause the remaining chlorophyll to be broken down more quickly revealing yellow and orange fall color. Similar conditions allow plants to produce pigments responsible for red and purple fall color. A moist growing season followed by a dry fall increases the quality of fall color. More explanation about the factors that play into fall color can be found at the following website by the United States National Arboretum.
The Science of Color in Autumn Leaves
