Did you know the fall color is always there?

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Fall color has been slowly bleeding into the tapestry of our landscape due to our little stretch of dry weather. It is a natural reaction for a plant to show signs of fall color early when it is under stress. In fact, we have some crabapples that are blooming because they have completely defoliated. No leaves mean the sun’s warmth coaxes bud break and bloom at the wrong time of the year.  Additionally, the lack of moisture and the plant’s ability to take up nutrients means that it uses up the chlorophyll in the leaves at a faster rate than it can be replaced. Early fall color (or complete leaf drop in the crabapple’s case) can be considered somewhat of a defense mechanism as the plant attempts to speed dormancy in order to save some energy under stressful growing conditions.
There are many factors that trigger the color change in foliage, but what you might be surprised to learn is that those reds, oranges, yellows and purples are always present in the leaves. In fact, the colors associated with fall are just hidden by the green color that chlorophyll produces.
We all expect leaves to be green in the summer, but have you ever wondered why?  Rosie Lerner, explains, “chlorophyll uses sunlight and carbon dioxide from the air to produce carbohydrates (sugars and starch), which the tree uses for food.” During the long days of summer, trees are continuously replenishing their supply of chlorophyll, which is needed to produce their carbohydrate diet. Like us, we need to eat if we are using calories.
Since trees need the sun’s rays to produce and process their chlorophyll it is not surprising that as the days grow shorter they use up their sources of chlorophyll faster than they can produce it. As the chlorophyll drains from the leaves the fall color is revealed; and the descent into dormancy begins.
Different species are associated with different colors during the fall. Some trees exhibit leaves that turn a fiery red, others yellow, orange or purple. What makes for the rainbow of colors underneath the mask of chlorophyll-green? Pigments called carotenoids (yellow, brown and orange), anthocyanin (reds and purples), and a combination of the two create the dramatic reds, bronze and bright orange found in sumacs and oaks.  
The carotenoid pigments are always present in the leaves, but the anthocyanins are produced later in the summer, triggered by cooler evening temperatures and shorter days. The ideal environment for the production of anthocyanin pigments are warm, sunny days (active chlorophyll production) because more sugars will be produced; and 45-degree nights (refrigeration of sorts) because the sugars remain in the leaves longer. More sugar means more intense colors.  
Some of the trees that I think have the prettiest fall color (and are good selections for our varying environments) include sumacs, service berries, sassafras, sugar maple, sweet gum and black gums, among many others. Now is a good time to take notice of the color choices that nature has to offer. Visit your local nurseries or Bernheim Forest if you have questions about what you see and you will be better informed about your choices and what they can offer you in the fall.
Planting trees while they are dormant is a good practice because the cooler soil temperatures allow the roots to establish without the added stress of having to put out new growth, new foliage, or bloom. If you want to add some trees to your landscape now is a great time to grab your shovel and start planting.