Q1.
Hydrangea is a plant that grows in cooler climates in the Himalayan region and the North-eastern states. It gives flowers of different colours, depending on the nature of the soil. Acidic soil produces blue-coloured flowers, whereas in basic soil, the flowers are pink or red. Can gardeners alter the colour of hydrangea flowers by adjusting the acidic or basic nature of the soil?
Answer
Yes, they can — and gardeners actually do this.
- To get blue flowers, the gardener makes the soil more acidic — for example by adding organic matter such as composted leaves or pine needles.
- To get pink or red flowers, the gardener makes the soil more basic — for example by mixing in lime (chuna).
Why it happens: the hydrangea flower contains a dye that behaves like an indicator, and the nature of the soil decides which form of the dye the plant carries into its petals. So the bush is, in effect, a living litmus paper rooted in the ground — the colour you see is a reading of the soil.
Did you know? The change is not instant. The plant has to take up the new soil condition through its roots, so a gardener starts treating the soil months before the flowering season.