Why do leaves change colour?
Quick answer from Eartha
Leaves change colour when it starts getting cooler and there's less sunlight. The green colouring, called chlorophyll, breaks down and fades away. Underneath, other colours that were hiding all along, like yellow and orange, get to shine through. That's why autumn leaves turn golden, red and brown.
The longer story
All through spring and summer, leaves are full of a green colouring called chlorophyll, which they use to catch sunlight and make food. This green is so strong it hides other colours in the leaf.
As days get shorter and cooler in autumn, some trees, called deciduous trees, slow down and stop making chlorophyll. Without fresh green colouring being made, the green slowly fades away.
Underneath the green, yellow and orange colourings called carotenoids were there all along, just hidden. Once the green disappears, these warmer colours finally get to show through.
Some leaves also make a new red colouring in autumn. Eventually the leaf dries out and drops off, ready for the tree to grow fresh green leaves again in spring.
Try this at home: leaf colour hunt
- Collect a few fallen leaves of different colours on a walk.
- Lay them out from green to yellow to red and brown.
- Talk about which colours might have been hiding underneath the green.
Words to know
- Chlorophyll
- The green colouring in leaves used to catch sunlight.
- Deciduous
- A tree that drops all its leaves at a certain time of year.
- Carotenoid
- A yellow or orange colouring hidden inside a leaf.
For grown-ups: what is my child learning here?
Age band: 8-11
Curriculum link: Australian Curriculum v9 Science, AC9S4U01
The concept: Living things, including plants, undergo growth and change influenced by seasonal conditions.
More classroom ideas are on our teachers page, and safety notes for families are on for parents.
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