Garden: The How and Why of Fall Foliage
The following is a regular column that addresses basic issues facing the ever-inquisitive back- and front-yard toiler, proffered by Brian Cruey, who as General Manager of Naumkeag for the Trustees of Reservations, knows about beautiful gardens.
Somewhere, buried deep in the depths of the memory graveyard known as my mom’s basement, there is a box marked “LEAVES.” Inside are hundreds of fall leaves that, as a kid, I collected and then forced my mom to preserve for me. Who knows how many countless hours that poor woman spent each autumn ironing dead leaves between pieces of wax paper. Not that I wasn’t selective – you had to be a pretty special leaf to make the cut, displaying either pure perfection or a flaw so awesome that it deserved eternity. Some of these treasures would be cut out and made into bookmarks, ornaments, note cards, or drink coasters that I would give out as Christmas gifts, but a lot ended up being tossed into that box because 1.) I would always make way too many and 2.) my mom couldn’t ever come to terms with throwing anything I made away. A tradition she continues even now when I’m well into my thirties.
I thought the whole thing was magic. The wax paper, for sure, but also the process of the changing of the leaves in general. Even at our youngest, the color palette that comes with every fall resonated inside of us, stirring emotion and imagination. I think one of the reasons that the phenomenon of autumn is so captivating year after year isn’t just because it’s beautiful, which indeed it is, but because it still conjures that same spark of wonder inside of us.
Of course, it’s not magic. It’s boring old science but that doesn’t make it any less amazing. The truth is, the vibrant colors that we see dotting our hillsides have, in some part, been there all season long. Leaves don’t exactly “change” color so much as they lose a color. That color of course being the green that we see all summer long. In the summer months, trees (and most plants) use the process of photosynthesis to convert sunlight, carbon dioxide, and water into oxygen and glucose – a type of sugar that the plant uses as food. Trees use their leaves to capture those elements (light, rain, and carbon dioxoide) and the leaves contain a chemical — chlorophyll — that makes the process of photosynthesis possible. It just so happens that the chlorophyll, more often than not, has a very dominant green pigment.
When the days start to get shorter and sunlight becomes less available, not only do people start shutting down their vacation homes, but trees start shutting down their sugar factories. The chlorophyll in a leaf, with all of its green pigment, fades away and reveals the yellows, oranges, reds, and browns that were there all along.
The color that remains is what we see in the fall, and it is a common design tool gardeners use to add interest to a landscape. There are many things to consider when choosing a tree for your home garden, which we’ve talked about before, one of those being fall color. Put the bright yellow autumn foliage of the Gingko Biloba against the reds of the Red Maple and the oranges of Witch Hazel, and you’ll have a color display that could rival any summer garden. Some plants are even named after their fall color, like the invasive burning bush that is so prevalent in this area and simply stunning this time of year. It’s not so rare for a plant’s greatest attribute to be its fall display.
Of course, we all know that some fall “shows” are better than others and the potency of that yellow and red is dependent on external factors. In general, the best fall foliage occurs in years when we’ve had a warm, wet spring, a summer that’s not too hot or dry, and a fall that has plenty of warm sunny days and cool nights — weather we are often lucky enough to experience most years here in the Berkshires, which is why people from all over pour into the region to see the amazing colors painting our gorgeous hillsides. Like most things, it’s just better in the Berkshires!