Transforms pink hydrangeas to blue, ideal for those looking to change their hydrangea's colour. Hydrangeas that grow in soil with iron or aluminium salts naturally develop blue flowers. This colourant provides a solution for achieving blue blooms, with pale pink varieties best suited for the colour change. Darker pink varieties may turn mauve or blue. For best results, ensure plants are in acidic soil; if your soil is alkaline, double the amount of colourant. Suitable for both pot-grown and outdoor hydrangeas. Mix with soil for optimal results during root development. After establishment, dilute the colourant as directed and water weekly during the growth period. Always keep out of reach of children and use protective gloves and eye protection when handling.