Hair Care Routine with Melanitis Castor oil Here's how to take care of your hair with castor oil, easily Give your scalp a drink: Put a few drops of castor oil on your scalp and rub it in gently. This helps blood flow better. Extra moisture (not a must): Castor oil is thick, so you can mix it with another oil like jojoba or coconut oil to make it thinner. Or, you can steep some herbs in hot water, strain it out, and mix that with the oil. Don't forget the ends! Rub a little bit of castor oil on the rest of your hair for extra moisture.