Hydrangeas

Hydrangeas are very sensitive to the soil in which they're planted.

This one caught my eye because in this area the soil type is not very acidic which means, no matter what colour it is in the garden centre, within a year it will have reverted to pink.

This one has been tricked into reacting to something copper (old piping below the roots or the use of Copper Sulphate Solution). It retains its rather striking blue colour.