Spraying rosemary water in your hair can provide several benefits for your scalp and hair health. Here are a few instances when you may consider using rosemary water:

1. Scalp Health: If you have a dry or itchy scalp, rosemary water can help soothe and hydrate it. Spray it directly onto your scalp after washing your hair and gently massage it in. Leave it on for a few minutes before rinsing it out.

2. Hair Growth: Rosemary water is believed to promote hair growth and reduce hair loss. You can spray it onto your scalp and massage it in to stimulate blood circulation, which can nourish the hair follicles. This can be done a few times a week.

3. Conditioning: Rosemary water can act as a natural conditioner, leaving your hair soft and smooth. After shampooing, spray it onto your hair, focusing on the ends. Leave it on for a few minutes before rinsing it out.

4. Refreshing Mist: If you want to refresh your hair between washes or after a workout, rosemary water can be used as a revitalizing mist. Spray it lightly over your hair to add a pleasant scent and provide a refreshing feeling.

Remember, rosemary water is generally safe for most people, but it's always a good idea to do a patch test first to check for any allergic reactions. Additionally, if you have any specific hair or scalp concerns, it's best to consult with a dermatologist or trichologist for personalized advice.