A Colorful Fall Could Be On The Horizon

Fall in the Hamptons is a very subtle season.

Because we receive more sunlight than any other area of the region, along with our very gradual cool down, the fall color changes are slow to happen. In some areas where pitch pines and scrub oaks dominate, the changes can easily be missed. Upstate, the large maple in my front yard begins to turn around Labor Day and is usually leafless by the third week in September, but it can be six weeks later before a sugar maple in Southampton begins to show the reds and oranges of the season.

As children we were secure and knowledgeable in the fact that Jack Frost was responsible for the riot of colors that move from our earthbound gardens up into the limbs, branches and twigs above. I have it on good authority, though, that Jack retired and is now living in a retirement community in Florida where he complains bitterly about the lack of seasons other than dry and wet.

The Native Americans, on the other hand, believed that celestial hunters slew the Great Bear in the autumn, and that his blood, dripping on the forests, changed many of the leaves to red. Other trees were turned to yellow by the fat that splattered out of the kettle as the hunters cooked the meat.

Fairy tales and legend aside, we now know that leaf color changes that take place this time of the year are due to chemical processes that occur within the trees as the seasons begin to move from summer to winter. All during the spring and summer, the leaves served as factories where most of the foods necessary for the tree’s survival are manufactured. This “food-making” process takes place in the leaf in numerous cells containing the pigment chlorophyll, which, from spring on, gives the leaf its green color.

Chlorophyll absorbs energy from sunlight and uses it in transforming carbon dioxide and water to carbohydrates such as sugars and starch. Along with the green pigment, leaves also contain yellow or orange carotenoids which, for example, give the carrot its familiar color. Most of the year these yellowish colors are masked by the greater amount of green coloring, but not in all plants. In the fall, however, partly because of changes in the period of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellowish colors become visible and give the leaves part of their fall splendor.

At the same time, other chemical changes may occur and cause the formation of additional pigments that vary from yellow to red to blue. Some of them give rise to the reddish and purplish fall colors of leaves of trees such as dogwoods and sumacs. Others give the sugar maple its brilliant orange or fiery red and yellow. And if you’re looking to infuse your landscape with a riot of all colors, a planting of several varieties of Japanese maples really do the trick out here and these trees can be as small as a few feet in height to 20 feet of spectacular color.

The autumn foliage of some trees, such as the quaking aspen, birch and hickory, show only yellow colors. Many oaks, on the other hand, will turn mostly brownish, while beech turns a golden bronze and holds its leaves through most of the winter.

One small Japanese maple that I observe every few days will go from a vivid blood red to a near orange and then seems to go into a yellow phase just before leaf drop. All this due to varying amounts of chlorophyll and other pigments that are about to peak.

If it’s the red autumn colors that you’re after, these usually take place after a few brilliantly sunny October days followed by night temperatures below 45 degrees. Much sugar is made in the leaves during the daytime, but cool nights prevent the movement of sugar from the leaves. From the sugars trapped in the leaves, the red pigment called anthocayanin is formed.

Familiar trees with red or scarlet leaves in the fall are red maple, silver maple, flowering dogwood, sweet gum, black tupelo or black gum, northern red oak, scarlet oak, sassafras and sumac. The vines of Virginia creeper and poison ivy can also provide striking shows of reds as well while the invasive bittersweet vine can be a vibrant yellow—though there is a native, noninvasive species.

The degree of color may vary from one tree or vine to another. For example, leaves directly exposed to the sun may turn red, while those on the shady side of the same tree or on other trees in the shade may be yellow. The foliage of some tree species just turns dull brown from death and decay and never show any bright colors.

One of the most striking examples of how a plant reacts to sunlight in the changing of its fall colors is the burning bush, or Euonymus alatus. A midsized shrub that makes a great specimen or screening plant, it will tolerate shade to full sun. But come October the plants growing in the shade show little if any change in leaf color before the leaves fall to the ground. But in full sun, the same plant becomes a vibrantly striking scarlet to flaming red glow that is unmistakable in the landscape.

Ah, but there’s a problem. Euonymus alatus is an invasive species and it’s illegal to sell or plant it in New York State. There are alternatives, though, that do provide similar fall color options such as the red chokeberry (Aronia arbutifolia), winterberry (Ilex verticilalata) and highbush cranberry (Viburnum trilobum).

Another interesting fact is that the colors on the same tree may vary from year to year depending on the combinations of weather conditions. When there is warm, cloudy, rainy weather in the fall, the leaves tend to have less coloration. The smaller amount of sugar made in the reduced sunlight moves out of the leaves during the warm nights. Thus, no excess sugar remains in the leaves to form pigments. Most broad-leaved trees in this area shed their leaves in the fall. However, the dead brown leaves of the oaks and the nearly translucent foliage of beeches and a few other species may stay on the trees until growth starts again in the spring.

Through the fallen leaves of all of the other trees, nature provides herself with a type of manna rich in calcium and potassium, which, if left undisturbed, again becomes an original part of the soil from which it originally came. Remember the saying “Leave the leaves,” but not on your lawn. Keep growing.