To use rosemary oil for hair, it is essential first to dilute it properly with a carrier oil (like jojoba, coconut, or olive oil) before applying to the scalp to avoid irritation. A common dilution ratio is about 6 drops of rosemary oil per tablespoon (15 ml) of carrier oil. Apply the diluted mixture directly onto the scalp using your fingertips or a dropper, then gently massage the scalp in circular motions for 3-5 minutes to stimulate blood flow. Leaving the oil on for at least 30 minutes before washing is recommended, and for deeper treatment, it can be warmed slightly, applied liberally, wrapped with a warm towel, and left on for 1-2 hours or overnight before washing out. Consistency in application, such as daily or a few times a week, is key to seeing benefits. Alternatively, rosemary oil can be added to shampoos or conditioners (about 5 drops per ounce of product) to incorporate it into a hair care routine more easily. Never apply pure rosemary oil directly to the scalp without dilution to avoid irritation. Regular, gentle scalp massage with diluted rosemary oil may help promote hair growth, improve scalp health, and reduce dandruff or dryness.