Hair Coloring : Darken Hair Pour 1 cup boiling water over 3 tbsp. rosemary. Let stand overnight and use as a final rinse. This really makes hair gleam and smells wonderful, as well as enhances curly hair. Hair Coloring : Lighten Hair Mix several tbsp. of lemon juice to 1 cup of water. Apply as a final rinse. Let hair dry in sun if possible. This is great for natural blondes and adds highlights to darker hair.