🍂 Why Do Leaves Change Colour in Autumn?

As the long, warm days of summer begin to fade, a spectacular transformation sweeps across forests, parks, and gardens: leaves turn brilliant shades of red, gold, orange, and even purple. But have you ever wondered — why do leaves change colour in autumn?

It turns out, this stunning display is the result of a fascinating blend of biology, chemistry, and survival strategy.

The Science Behind the Colours

During spring and summer, leaves are filled with a green pigment called chlorophyll. Chlorophyll is essential for photosynthesis — the process plants use to convert sunlight into energy. It absorbs sunlight, helping the plant make the sugars it needs to grow.

However, as autumn approaches, days become shorter and temperatures drop. Trees begin to prepare for winter, when there’s less sunlight and water available. To conserve energy and survive the harsh months, trees stop producing chlorophyll. Without chlorophyll constantly being made, the green colour fades — and that's when the hidden colours begin to appear!

Underneath the green, leaves actually contain other pigments all along:

• Carotenoids produce yellow and orange colours (also found in carrots and corn!)

• Anthocyanins create reds, purples, and deep blues

• Tannins give leaves a brown colour (especially seen in oaks)

Interestingly, while carotenoids are always present in leaves, anthocyanins are often produced only in autumn — meaning some of the most vivid reds and purples are special creations just for fall!

Why Bother with All the Colour?

Scientists believe that the production of anthocyanins might serve several purposes:

• Protection: They may help shield leaves from too much sunlight while the tree reabsorbs nutrients like nitrogen.

• Pest Defense: Some researchers suggest that the bright red colour might deter insects from laying eggs on dying leaves.

• Waste Management: As leaves shut down for winter, anthocyanins could help manage waste products and stress.

In short, autumn colours aren’t just pretty — they’re part of an essential survival strategy!

Why Are Some Autumns More Colourful Than Others?

The intensity of fall colours depends on several factors:

• Temperature: Warm days and cool (but not freezing) nights tend to boost red and purple colours.

• Moisture: A dry summer can lead to early, less vibrant colour changes, while a wet growing season supports a fuller display.

• Sunlight: More sunny days help increase sugar production in leaves, which enhances red pigment formation.

That’s why some years, forests explode in fiery hues, while in other years, the colours might seem more muted.

🌟 My Perspective

There’s something magical about the way trees let go of their leaves — not with resistance, but with incredible beauty. Autumn reminds me that change, even when it signals the end of something, can be filled with colour, richness, and life.

When I was younger, I used to think that trees "got tired" and that’s why their leaves changed. Now that I understand the science behind it, it feels even more awe-inspiring. The trees aren't giving up — they’re preparing carefully for what’s ahead.

It’s a beautiful metaphor for life too: sometimes we need to shed what we’ve outgrown, make space for rest, and trust that new growth will come when the season is right.

If you could design your own tree species, what would its leaves look like in autumn? Would they sparkle, glow, change to neon colours? Let me know in the comments!