Why Do Leaves Change Color?

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Leaves usually change color in the fall season. They change from their usual color of green to other colors like yellow, brown, bronze, gold, orange, and red. The color change occurs before the leaves finally fall off the trees and shrubs.

Leaf color

Leaf color usually comes from pigments within the leaf. There are three major pigments in the leaf namely chlorophyll, carotenoid, and anthocyanin.

Chlorophyll is the pigment that gives leaves their green color. It helps plants to manufacture their own food through the process of photosynthesis. The chlorophyll in the leaves absorb energy from sunlight and this energy is used to convert carbon dioxide and water into sugars like starch and glucose which provide food for the plant.

Carotenoid on the other hand is the pigment that gives plants the orange or yellow color. Fruits and vegetables which have bright yellow and orange colors owe their colors to carotenoid. Examples of these fruits and vegetables include oranges, mangoes, bananas, pawpaw, carrots and pumpkins.

Anthocyanin on its part is the pigment that contributes to the red color in plants. The red color due to anthocyanin is evident in fruits and vegetables such as tomatoes, plums, red apples, cranberries and strawberries.

What causes the color change in leaves?

Before we can look into the causes of color in leaves especially in fall, lets first understand why leaves usually have their normal green color in other seasons like spring and summer. The reason for this can be explained by the availability or non-availability of the leaf pigments in the plant at a particular time.

Chlorophyll and carotenoid are usually available in the plant at all times. Chlorophyll however covers carotenoid in the spring and summer seasons and hence, the green color from chlorophyll dominates leading to the leaves being green in spring and summer. Anthocyanin is however only produced in fall under special conditions. Besides, not all plants are capable of producing anthocyanins.

Coming to the change of color in leaves, various explanations can be given. These include color change due to factors such as sunlight and temperature among others. Rainfall also affects color change in leaves.

Color change due to sunlight

As the earth revolves around the sun, the availability of sunlight in certain parts of the world is affected. Certain places receive less sunlight at a particular time of the year due to revolution of the earth. The days become shorter in this places and the nights become longer. Temperatures also reduce and the fall season sets in.

Most plants respond to the low amounts of sunlight by producing less chlorophyll and eventually stopping its production altogether. In the absence of chlorophyll, the carotenoids which are usually present in the leaves throughout get a chance to dominate in the leaves. The leaves therefore change into colors like orange, brown, gold and yellow.

Temperature and color change in leaves

Cool temperatures at night in fall cause leaves to turn red in some plants. During sunny days in fall, plants manufacture sugars in their leaves. The cool night temperatures however hinder the sugars from being transported to other parts of the plants. In order to ensure that other parts of the plant also access the nutrients, anthocyanins are produced to help extract nutrients from the leaves before they fall off. The leaves thus turn red because of the anthocyanins.


Presence of rain in fall lowers the intensity and brightness of leaf colors. Lack of rain before fall also delays the onset of color change in leaves. A warm, sunny fall gives the best color change.

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