Westland Hydrangea Colourant 500g

Hydrangeas have a party trick most flowers can't match — change the soil chemistry, change the bloom colour. Westland Hydrangea Colourant acidifies the soil around pink varieties, turning them a genuine blue, or darker pinks to mauve-blue, using a combination of iron and aluminium salts.

Works best on plants already growing in acid soil; for alkaline soil, pair with an ericaceous compost or simply double the application rate. A fun, slightly alchemical way to change the whole character of a border.