Mole Repellent Spray. A simple mixture of 1/2 cup of castor oil and 1/2 cup of liquid dish soap will keep moles at bay. Combine the two ingredients in a jar and keep this on hand. When you're ready to use the repellent, mix 3 tablespoons of it with a gallon of warm water. Pour this solution into a watering can and then pour it on the areas of the garden where you don't want moles to go. You don't need to saturate the area with the solution, just dampen it.