Hydrangeas that grow where iron or aluminium salts are present tend to change colour and produce blue flowers. Depending on the variety, pale pink hydrangeas will turn blue best with darker pink varieties turning to mauve or blue.
Features:
Hydrangeas growing in the presence of iron or aluminium salts which will tend to change colour and produce blue flowers
Varieties naturally pale pink tend to blue best, the darker pink varieties turning to mauve/blue
Best results are obtained with plants growing in acid soil