Rosemary-Sage Natural Hair Dye For covering gray hair. 1/2 cup dried sage 1/2 cup dried rosemary 2 cups hot water Combine all ingredients in a nonreactive saucepan. Simmer for 30 minutes, then steep for several hours. Strain, and then use the resulting liquid for the colorant. Apply to hair and leave on until dried. Rinse and dry. Repeat weekly until you obtain the desired shade, then monthly to maintain color.