December 4, 2017 /
Jona Elwell

No, Your Eyes Aren’t Deceiving You. Leaves Stayed on the Trees Longer

Ho boy. Fall has been quite a roller coaster this year, huh? And I’m just talking about the weather. With an incredibly warm October, it seemed that fall foliage was doomed. In many places across the country, including the DMV, trees were either changing colors much later than usual, or simply turning brown and immediately dropping.

But now, it’s December, and your eyes are not deceiving you. There are still beautiful, colorful leaves on trees. What gives?

Typically, September and October bring shorter days and cooler temperature that trigger the process that leads, eventually, to trees dropping their leaves. We had the shorter days, as always during early fall, but not the cooler temperatures. October and November were some warmest on record for most of the country. In the last week of November there was not only still rich fall foliage on most of the trees throughout the DMV, but the warm weather held on tightly, with one day reaching nearly 70 degrees. In late November!

That warm spell tricked the trees into holding off their annual changes. And then?

Cooler temperature arrived quickly (we all know they didn’t stay for long) and the layer of tissue called the abscission layer that develops at the base of each leaf stalk, where it connects to a stem, didn’t get a chance to develop. That layer that allows the leaf to be shed.

Ultimately, you can thank our changing climate for the stubborn foliage that’s causing this year’s late-season leaf crunch, said Laura Jull, horticulture professor and extension specialist for woody ornamentals at the University of Wisconsin-Madison.

Just like the fall foliage arriving, the leaves will eventually fall. It will just be later. We’ll see what winter brings – Capital Weather Gang is predicting that our warm start to December won’t last.