Why Leaves Change Color in Autumn

Green leaves turn red, yellow, and orange every autumn. This colorful show happens because of changes in weather and plant chemistry.

Trees use green pigment called chlorophyll to make food. Chlorophyll uses sunlight, water, and carbon dioxide to create sugar during spring and summer. Leaves look green because chlorophyll absorbs red and blue light, reflecting green light.

Leaves also contain other pigments all year: carotenoids make yellow and orange, while anthocyanins make red and purple. Chlorophyll hides these colors during warm months because green is abundant.

Days grow shorter and temperatures drop in autumn. Trees sense this seasonal shift. They prepare for winter by stopping food production. Chlorophyll breaks down and disappears.

Yellow and orange carotenoids, previously hidden by green chlorophyll, finally appear. Red anthocyanins form newly inside leaves from trapped sugars in bright autumn sun.

Trees eventually seal connections to each leaf. Leaves fall to the ground. Trees survive cold winter months without leaves by saving energy.

What is your favorite autumn leaf color?