ANNAPOLIS — Kiss the green leaves of summer goodbye and prepare for a fall chock-full of deep magentas, flashy oranges, bright reds and luminous yellows.
Drought conditions in the state from 1997 to 1999 that left trees parched made for less-than-notable foliage changes in those years, but the buckets of rain dumped across Maryland this summer have set the stage for a “brilliant” fall, state foresters say.
“The trees are fully healthy and happy this year – not under stress like last year,” said Don VanHassent, supervisor of forest stewardship for the state Department of Natural Resources.
“It should be a nice fall, foliage-wise,” he said.
Fall will not officially begin until Sept. 22, but leaves in a few swampy areas of western Garrett County already have begun changing color. But that’s the exception at this point, said Dorcas Coleman, who runs a DNR hotline, 800- LEAVES1, that gives weekly updates on leaf conditions during the fall.
Traditionally, the bulk of the leafy transformation begins in the western parts of the state by the third week of September and gradually spreads south and east through October. State foresters expect the change will occur within that general time frame this year, though weather conditions could slightly alter it.
In Western Maryland, peak viewing conditions are expected around the second week of October.
Leaves in Southern Maryland and on the Eastern Shore should peak later in October and into November.
The bright colors become visible in the fall as plants begin to shut down for the winter and slow their production of chlorophyll. Chlorophyll produces the bright green pigment that colors leaves throughout the spring and summer.
During the spring and summer months, the green pigment masks the red, yellow, and orange pigments also present in leaves. As chlorophyll production ceases, the green disappears and the other pigments become visible, according to state foresters.
Weather plays a large role in determining the brilliance of the colored leaves and the length of time they hang on the trees before dying. Foresters point to three criteria required for optimum viewing conditions.
First, the trees must enter the fall healthy, which the abundance of precipitation this year – 29 inches at Baltimore-Washington International Airport through July, over 20 percent higher than normal – has ensured.
“In last year’s drought, the foliage started to turn a little earlier and many leaves turned brown and dropped,” without ever turning color, VanHassent said.
Between January and July 1999, 19 inches of precipitation fell at BWI, roughly 20 percent less than normal.
Second, the days in September and October must be warm and sunny and the nights cool and crisp without a frost.
Lastly, a spell of hot weather that hits in late September could drastically shorten the prime viewing period.
“A plant’s biological clock follows a natural progression as it gradually gets cooler and the days gradually get shorter,” said Mike Galvin, supervisor of urban and community forestry for DNR.
“But, if in the third week of September we get an unnaturally warm temperature, the plants go, `Hey, what’s going on?'” he said.
Chlorophyll production increases, meaning the leaves stay greener longer. But the viewing season does not extend. “The leaves will drop around the same time every year, regardless,” Galvin said.