Westland Hydrangea colorant is a Salt which changes the colour of pale pink Hydrangea varieties to blue and darker pink varieties to mauve blue. However, some hydrangeas are bred to be pink in all soil conditions and will not change colour so it is worth checking the plant label. Best results are obtained with plants growing in acid soils where the soil is naturally Alkaline use ericaceous compost instead or double the application rate.
Changes pale pink hydrangeas to blue.
Changes dark pink hydrangeas to mauve blue.
Will enhance the colour of any line hating plant.