Changes the flowers of pink hydrangeas from pink to blue and with regular application keeps the colour change all season long.
Hydrangea flowers grown in alkaline soils will produce pink flowers. Doff Hydrangea colourant can change the flowers colour to mauve/blue by changing the soils to acidic levels. This process can take a few weeks and may also need application in the current season to produce the change for the next season.
Always read the label.