TINTED HAIR - RETOUCH AND REGROWTH. Apply the colour to the roots (leave for 10 min.). To ensure a uniform effect then wet the hair and lather the colour previously applied to the base (roots) to the length and ends of the hair. Leave for a further 10 min.
Does the word 'regrowth' mean that the product will cause new hair to grow or does it mean applying the product to the roots?
It won't cause your hair to grow. When your hair does grow on its own, though, the un-dyed roots are going to show. So these instructions are for touching up the roots.