Falling for Autumn

Fall leaves on Independence Ave SE, Washington DC 2009. Photo by J. Harbster

 Growing up in California I never got to truly celebrate the changing of the seasons on the grand scale. But now that I am on the East Coast, I get a first hand account of each season- from the cold and snow of winter, into the flowers of spring, followed by the heat of summer and finally the brilliantly colored leaves of fall.  I know I am not alone when I say that there is something about the beginning of autumn that gives a warm cozy feeling inside- the nights grow longer, the days get cooler, the football season starts, the holidays are right around the corner and the deciduous trees put on a show of vivid colors before they drop their leaves.

 Typically around this time of year we receive questions about why leaves change colors. In response, we created a guide to help answer some of these questions:

The Nature and Science of Autumn

Generally speaking, due to the decrease of daylight, the chlorophyll, which make leaves green, production slows down. Once the chlorophyll production stops, the anthocyanins (which give plants red and purple color- think cherry) and carotenoids (which give plants orange color- think carrot) show their vibrant fall colors.

 We entered the autumnal equinox on Wednesday, September 22 at 11:09 pm, though here in DC we are having a heat wave (today we should reach 97 degrees), so it is not easily apparent that we have crossed into the crisp cool days of fall. But as I walk the neighborhoods of Capitol Hill I notice the poplar trees are rehearsing for their fall foliage show, with the green leaves turning yellow. You might not be aware of it, but in the 19^th century Washington DC came to be known as the City of Trees and Capitol Hill (where the library sits) boasts over 4,200 trees.

Fall leaves, Independence Ave. SE, Washington, DC 2009. Photo by J. Harbster.

 The peak fall foliage does not usually begin until October, so there is plenty of time ahead to get out and enjoy the colors of the season. If you live in the US and want to find an area near you to view fall foliage, see the USDA Forest Service fall foliage hotspots , which includes a fall color hotline!

 If you live in an area where you cannot view the changing colors of fall leaves, the US National Arboretum in Washington DC has a gallery of fall foliage for you to enjoy.