Now that fall is upon us, many can’t wait to see the beautiful fall color the Mid Atlantic has to offer. Last year, the color was much later than it typically is due to the warmer than normal temperatures. The past three years of 2015, 2016 and 2017 all experienced top 10 warm fall temperatures, making for a later color change.
What about this year? I reached out to Joe Rossetti, the Senior Area Forester and James McGlone, Ph.D. Urban Forest Conservationist at the Virginia Department of Forestry to ask a few questions.
When asked how the process works, they explained,
“Fall color is seen when the green chlorophyll is broken down in the leaves revealing the yellow and orange carotenoids which were present all year long, and the red anthrocynins produced in the fall. All of the chemicals are anti-oxidants produced as stress reactions, but the production of these chemicals need energy.”
What are some of the factors that help produce the best fall color?
“The diurnal temperature differences in the fall are a stressor, so the larger those swings but without a frost, the better the color. Bright days are also important because the trees then get plenty of sun to product the energy needed to make the yellow, orange, and especially red pigments. “
Will the excess precipitation we’ve had this year play a role?
“The super wet year by itself is not a stressor on most trees. Incidence of bacterial leaf scorch on the Red, Black and Scarlet oaks has been a little higher than normal this year, so the amount of deep red from these common trees across the landscape may be reduced this year.”
Overall, the two peak factors are temperatures in the fall months along with the loss of daylight. Washington D.C. loses an hour and thirteen minutes of daylight from the 1st through the 31st of October, averaging near 15 minutes per week. While this is constant from year to year, temperature variations usually aren’t.
The first few weeks of October are expected to be well above normal with highs around 10 degrees above normal. With this being the case, we can expect some change in the higher elevations through early October and the peak more than likely mid to late October.
For the D.C. Metro, we would anticipate some color change beginning here over the next few weeks, but don’t expect full on spectacular fall color until the beginning or middle of November. With temperatures this warm, we’ll have a ways to go until we reach our peak.