Last Sunday marked the start of a colorful time of year – the start of Fall Foliage Week! While Summer is definitely my favorite season climate-wise (put me in warm, dry heat ANY day and I’ll be a happy girl!!!), Autumn holds a special place in my heart since I love all things colorful!

What makes Fall colors so spectacular and why are certain locations known for their foliage displays?

Well, let’s start with HOW the color change happens. In the growing seasons, the trees acquire energy through a process called photosynthesis. Short story – Sunlight hits the green leaves and the chlorophyll (the green pigment) becomes excited. This excitement, when water and CO2 are added, helps create energy for the plant, which keeps the plant happy and healthy! Unfortunately, the vibrant and plentiful chlorophyll pigment requires a ton of energy to create and sustain, so as the days get shorter in the fall, light becomes more scarce and the production of energy does not outweigh how much energy it takes to sustain the chlorophyll. The tree reabsorbs the chlorophyll, saving it for the next growing season, and reveals the other pigments who were visually drowned out by the chlorophylls vibrant coloration and sheer quantity. And… Ta-Da! You’re left with the yellows, oranges, and reds of autumn!

Some years, the leaves seem dull or lack-luster. Other years, the colors are brilliant! What changes?

As the leaves start to change, clear skies and crisp nights help the leaves put on their best color display. While the exact science is rather long-winded and complex, the short answer is: The clear skies allow for the tree to still obtain sunlight and create the energy needed to maintain it’s current pigment line-up, and the crisp (but not freezing!) nights help to ensure that the energy doesn’t get the chance to “move” too far away from the leaf. If there is too much rain or wind during the summer, and excess leaf-drop occurs, the fall foliage may not be as vibrant, since the leaves are now working doubly hard just to keep up energy production and the drop in temperature and sunlight can more severely impact the tree. On the other hand, if there is not enough rain in the summer, photosynthesis will not be as efficient and energy production will be low, preventing the leaves from creating the quantity and quality of pigments needed for a beautiful fall landscape.

Certain areas, like hill and mountain regions that experience a “Rain Shadow”, may have beautiful coloration on one side of the mountain, and a less stunning view on the other side. Rain shadows are caused by clouds dumping their water on one side of the mountain before they cross onto the other side. Areas near bodies of water like lakes and rivers may be rather spectacular since trees would have a more reliable source of water to use.

This year, remember to get outside and experience the beauty of the autumn season and witness nature’s amazing ability to adapt and stay strong during transitions and changes!

Want a hands-on experience with leaf pigments and colors? Check out my “Leaf Pigment Chromatography” DIY experiment that you can do with your kids, students, or on your own to discover the amazing colors hidden within a leaf. You can also learn more about plant anatomy and the purpose of their pigments during one of my Botanical Illustration Workshops – click here to find out when the next one is!