Fall Gingko
Garden Clippings for November 13, 2021
Friday morning at 8 am the Gingko leaves began to fall. By midafternoon there were only a dozen leaves left on the tree.
The day earlier, Thursday, was a windy day, but the Gingko tree hung on to its leaves for dear life. On Friday there was not a breath of wind in the air, and the leaves dropped like snowflakes at the Gingko’s base.
Trees have a mind of their own. In my back forty, the Walnuts have lost nearly all their leaves. Ditto for the Boxelders who have dropped their leaves, leaving their brown seeds on the tree.
The neighbour’s sour Cherry and Norway Maples are still as green as grass. The Maples will soon turn yellow and drop their leaves a week or two later. Oaks began turning colour a few weeks ago, but like they always do, Oak leaves will continue dropping till nearly Christmas.
The forest in the short drive along Highway 402 between Wyoming and Watford still reveals a display of colour that rivals the colours found in Algonquin. Within the next week or two all leaves in the bush will have dropped, save for the native Beech that won’t let go of their leaves until April.
Fall of 2021 will go down in the history books as the latest, longest and most colourful falls ever. Normally by the time Halloween arrives, the lawns, sidewalks and roadways are littered with fallen leaves. Not this year.
We tend to think that cold weather is the trigger that causes leaves to fall. While weather does play a role, the primary cause of leaf drop is day length. In mid-June the sun rises at 6 and falls after 9, but by November the sun rises at 8 and drops at 6, chopping off more than 5 hours of sunshine.
The science behind the growth of trees and their leaves is both complicated and amazing. Trees need light in order to produce chlorophyl, the pigment in leaves giving green colour. All is well when there is lots of sunshine, but when daylight is reduced, the production of chlorophyl goes downhill, revealing the true colour of leaves.
The theory behind this year’s late and long lasting leaf colour likely has to do with the more-than-usual sunshine we’ve enjoyed in the last few weeks. The first half of October was dreary with more cloud and rain than usual. But the past weeks have brought sunshine day after day.
The other factor affecting leaf colour is stress. Trees that are growing vigorously will keep their green colour long, while trees under stress because of disease or poor growing conditions can begin to turn colour as early as August.
In the forest, the trees that offer the most fall colour are Red Oak, Aspen, Dogwood, Hickory and Sugar Maple and Sumac. For home gardeners, Autumn Blaze and Sugar Maple are top choices followed by, Birch, Beech, Sweet Gum and Dogwood. For brilliantly coloured small trees the big family of Japanese Maples are winners along with Juneberry, Burning Bush and Flowering Dogwood.
