Mole Repellent This recipe is designed to repel those critters that tunnel through your yard. 1/4 cup castor oil 6 tablespoons water 2 tablespoons liquid detergent Blenderize the castor oil and detergent until the mixture is like shaving cream. Add water and mix again. Fill a regular garden sprinkling can with warm water and add 2 tablespoons of the castor oil mixture. Stir and sprinkle liquid over areas of greatest damage. For best results apply after a rain or a thorough watering.