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Why Do Leaves Change Color in the Fall?

Why Do Leaves Change Color in the Fall?

March 25, 2016

Where does the color come from in leaves, and why do they change in the fall?

It's amazing how complex the answer really is, so we are only covering the basics.

There are 3 pigments in leaves:

  • Chlorophyll gives leaves their green color. Chlorophyll does more than produce color, it catches the sun's ray and converts them to food (photosynthesis.) Chlorophyll dominates carotenoid which is why leaves have a green color.
  • Carotenoid gives leaves yellow, orange and brown colors. Carotenoid is also found in fruits and vegetables such as carrots, bananas, squash and sweet potato.
  • Anthocyanins gives leaves leaves red, purple and magenta colors. Anthocyanins is also found in fruits and vegetables such as purple tomatoes, acai berries, cherries and strawberries. Not all trees produce anthocyanins, and those that do, it normally only occurs in the fall. It is found with trees that have a sugary sap, such as maple.

    When summer ends, the days get shorter, and the nights get longer and colder as well. During winter there is not enough water or light for photosynthesis, so trees live off of the food stored during the summer. Green chlorophyll production is minimal, so the green color fades and allows the carotenoid and anthocyanins to come through.

    What happens to the leaves once they have fallen? They break down and provide nutrients for the soil.

    As we have mentioned in previous blogs, every fall foliage season is different, with Mother Nature being very unpredictable. For example if there is an early frost, it can turn the leaves brown and cause them to fall early. A lot of rain can lower the brightness of the leave's colors.