How do plants know when it’s Autumn? How do leaves know when to turn red and fall off?

Question

How do plants know when it’s Autumn? How do leaves know when to turn red and fall off?

In: Biology

Answer 1

There is a chemical called auxin which plants produce, this chemical is broken down by sunlight so long nights and short days increase the amount of auxin and the plant “knows” winter is on the way.