Hello again Garden enthusiasts,
What causes leaves to turn color in autumn?
Basically, there are two factors, shorter days and cooler temperatures. During the summer months, the leaves are green because of the pigment chlorophyll. The leaves are intaking sugars and carbohydrates for growth. When autumn arrives, especially in the Northern Hemisphere, leaves quit making chlorophyll and spectacular colors of crimson, glowing orange and yellow appear.
Here in Los Banos, I have noticed that the weather begins to cool, and some color can be seen by the second week in November.
Trees here that give a good display of autumn colors are the Chinese Pistachio; the Modesto, White and Raywood Ash; American Sycamore; Scarlet Oak; American Sweetgum or Liquid Amber and the Ornamental Pear. Of this list, my favorites are Scarlet Oak and Modesto Ash.
Unfortunately, our zone is too hot, making it almost impossible for Maple tree cultivars. Maple cultivars will grow, but as soon as we have temperatures of 95 and above, leaves burn and get crispy.
The Scarlet Oak is a beautiful tree, often not dropping all its foliage until spring. This makes it possible for birds to roost and hide from predators.
Most of our tree population having outstanding autumn color is the Modesto Ash. Unfortunately, over the years, these majestic trees have not been maintained correctly; this includes pruning for structural, root pruning, pesticide and fertilizer injection.
So, when the trees begin to display their beautiful autumn colors, take the time to either drive or walk the neighborhood streets.