Why do flowers change colour?

Flower colour can change, depending on external factors such as the soil conditions, the flower's age and nutrition level.

Soil conditions

One such plant is the big-leaf hydrangea. It changes colour when there are changes in soil conditions. In acidic soil, the plant produces blue flowers, while in alkaline soil, the flowers are pink! For more neutral soil conditions, the plant can produce lavender, blue or pink blooms all on the same plant. Have you tried the colour changing flower activity in the Secret Garden box? What turns the solution acidic?

Plant age

Some flowers change colour after pollination. First, its bright colours attract pollinators and indicates that the plant is full of nectar and pollen. Once the flower has been pollinated and is past its pollination stage, its colour changes and becomes less attractive to insects.

There are many other reasons why flowers change colour. What other reasons can you think of?

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