Why Do Leaves Turn Color in the Fall?
This is right up there with ‘how do they grow seedless watermelons?’ among the most-asked questions directed at plant professionals. The answer is simple! The days get shorter, the nights get colder, and Jack Frost magically paints the.Well, actually, the answer is more complicated, involving daylength (actually nightlength), temperature, nutrients, and genetics. Trees that have adapted to cold winter climates go through several steps as winter approaches. The first part of the process is a reaction to longer nights. The plant forms a layer at the base of the leaves that blocks the movement of carbohydrates (sugars, starches) out of the leaves, and blocks the movement of minerals into the leaves. That ‘abscission’ layer eventually gets brittle and breaks, so the leaf falls. But before that happens, the plant produces less and less chlorophyll because it has less stuff to make it from. That is the pigment which makes leaves green. It is also the most fragile pigment, breaking down in su
Leaves are actually little “factories” that manufacture food to help the plant grow. In the spring and summer, these factories run at top speed, taking in carbon dioxide from the air and water from their roots. Then sunlight enters the leaf and sets the factory in motion. But a leaf could not begin its manufacturing process with
