The Changing of the Guard: Fall Color and Trees

During the past several weeks we have experienced almost ideal conditions for an outstanding fall color display.  The days have been warm and sunny and the nights have been cool to cold, but not freezing. It is under these conditions that sugars are produced in the leaf (these are important because they trigger the amount of anthocyanin pigments which produce red colors and because the carotenoids produce yellow and gold which remain fairly consistent) and during the night the gradual closing of the veins in the leaf don't allow the sugars to escape or move out of the leaf. So as the chlorophyll, which gives the leaves their green color, begins to slow down production and eventually stops as the length of night time increase, the other pigments show their colors after being masked by the chlorophyll.

Each group or species of tree typically exhibits a different palate of colors:

Oaks turn red, brown, or russet;

Hickories turn drab yellow to bronze;

Green ash turns yellow and white ash turns purplish;

Red maple turns scarlet red, sugar maples turn orange to red, and black maple turns brilliant yellow;

Sassafras turns orange to red;

Sourwood and black gum turn crimson red;

Flowering dogwood turns purplish-red;

and tulip poplar turns yellow.

Some species like the elms, don't turn color much at all and just shrivel up and drop their leaves.

One of the most fascinating things about using trees in the landscape for fall color is that some species, like red maple, are genetic clones and driving along US 60 from Versailles to Frankfort I noticed plantings of red maple and they all looked identical.  They all had a similar looking canopy. All had three primary limbs coming from the trunk and all were pointed in the same direction and had the same shape, and all were turning color, the same color, and the color was turning from the same direction and amount of coloration in the leaves was strikingly similar.  In short, they looked identical and most likely were clones that were selected for their fall color because they were beginning to turn a brilliant crimson red and in a week will be quite strikingly beautiful, especially when dropped against the bright green grass in the horse pasture.

If you are looking for great fall color in your  yard, look at the list of trees above and think about what species you might like to add just for color's sake.