The Colors of Autumn

    • Tree collards are delicious winter vegetables. Set out plants now.
    • Enjoy birds in your garden by hanging bird feeders around the yard. You’ll see many different kinds as they migrate through this fall.
    • Fragrant Paperwhite narcissus will bloom indoors by Christmas if planted now in rocks and water.
    • Clean up dead foliage on perennials like peonies, daylilies and balloon flower and cut back dead flower stems on Echinacea, blanket flower and penstemon.
    • Japanese maples and snowball bushes are some of the most colorful shrubs in the fall. Plant them now and give them a head start on spring.

The Colors of Autumn

We all enjoy the colors of autumn leaves. The changing fall foliage never fails to surprise and delight us. Did you ever wonder how and why a fall leaf changes color? Why a maple leaf turns bright red? Where do the yellows and oranges come from? To answer those questions, we first have to understand what leaves are and what they do.

Leaves are nature’s food factories. Plants take water from the ground through their roots, and carbon dioxide from the air. They use sunlight to turn water and carbon dioxide into oxygen and glucose through photosynthesis. Chlorophyll, which gives plants their green color, helps make photosynthesis happen.

The shortening of daylight hours and cold, crisp nights triggers the trees to go into dormancy. During these days, lots of sugars are produced in the leaf but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out. During the winter months they will live off this stored food.

As the green chlorophyll disappears from the leaves and the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can’t see them in the summer, because they are covered up by the green chlorophyll. Ginkgo, birch, aspen and willow trees turn a dazzling yellow in the fall.

The vivid red and purple colors in scarlet red maples, sweet gum and dogwood trees are made mostly in the fall. Reds and oranges are made by different pigments, called anthocyanins. Anthocyanin pigments are responsible for the red, purple, and blue colors of many fruits, vegetables, cereal grains, and flowers.

Chlorophyll requires sunlight and warm temperatures to do its work. As chlorophyll exits the leaves, anthocyanins are created to give leaves time to unload nutrients. The new red pigments protect leaves from the sun, giving some species extra time to absorb those essential leaf nutrients.

If you’ve ever noticed maples turn a deep burgundy before they achieve that crims
on red, it’s because the burgundy is a mix of outgoing green chlorophyll and incoming red anthocyanins, and the crimson is pure anthocyanin.

While leaves will always change color as the amount of sunlight wanes, weather conditions can affect how brilliant they become. High heat or drought can rob leaves of their brilliance, or make leaves drop early. Insufficient rain in September can also hurt peak color. But lack of wind and rain in the autumn will prolong the display.

It is the combination of all these things that make the beautiful fall foliage colors we enjoy each year.

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