Why Do Leaves Change Color in the Autumn?

Seasons are a beautiful natural miracle that occur every year. For many countries around the world, the change from summer to autumn is very noticeable when looking at the trees. But have you ever asked yourself why do leaves change color during autumn?

Today at Bios Urn® we are going to take a look at what gives us these beautiful colors during the fall and what factors impact those colors.

The first signs of autumn

Autumn officially starts around the 21st September each year. However the first signs of the new season can be appreciated in nature earlier.

Autumn is a season of change from summer to winter. It is known as Fall in some parts of North America because of the falling leaves of deciduous trees.

The air begins to feel crisper, especially in the morning. Temperatures begin to drop and morning dew begins to appear.

So why do leaves change color in the autumn? Well when autumn starts moving in, the days also start getting short and the nights start to get longer. This is when the chlorophyll starts to break down.


Bios Urn Blog: Why do leaves change color in the autumn?

Image source: CC0 Public Domain

What is chlorophyll?

Chlorophyll (also chlorophyl) is a green pigment found in plants. Plants use chlorophyll and light to make food.

During the spring and summer the leaves have served as factories where most of the foods necessary for the tree’s growth are “manufactured”. This food-making process takes place in the leaf in numerous cells containing chlorophyll, which gives the leaf its green color.

So why do leaves change color in the autumn?

In the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor.

The carotene will start to show through as the chlorophyll breaks down. And they come out in those yellows and browns that we are used to seeing on trees.

And how about those beautiful red colors everybody looks forward to seeing in the fall? This red pigment is actually caused by anthocyanins.


Bios Urn Blog: Why do leaves change color in the autumn?

Image source: Flick Don Graham

What creates the most beautiful autumn show?

There are 3 factors. You need an ample moisture-filled growing season. That leads into a fall with dry, sunny days and cool, dry nights

Enjoy the color, it only occurs for a brief period each fall!


What do you think of the reason why leaves change color in the Autumn? had you heard about it before? We would love to hear from you in the Comments section below!

You may also be wondering when is the best time of year to plant your Bios Urn®? Check out all of our planting tips here.

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  1. Prof. Brian J Ford says

    Leaves act as the plant’s excretory mechanism – that’s why they are shed in the fall. I called them ‘excretophores’ in my publication in Nature.

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