A digging mole aerates the soil and devours harmful pests, but it can also leave unsightly humps in the yard or uproot plants. Dangerous traps and poisonous chemicals are illegal in many areas, making repellents a better option for mole control. Harnessing the repellent properties of castor oil, a common ingredient in commercial mole repellents, allows you to create an effective homemade solution to a mole problem.
Measure 1/2 to 1 cup of castor oil into a glass jar. Add 1/2 cup of liquid dish-washing soap. Place the lid on the jar and shake the solution until it begins to foam. Label the jar with the contents.
Fill a spray bottle or watering can with 1 gallon of warm water.
Add 2 or 3 tablespoons of the concentrated castor oil solution to the water in the bottle or can. Stir or shake the solution until it is completely combined.
Step on and collapse any visible mole tunnel humps in the garden or lawn before applying the repellent. Collapse entrance and exit holes in garden beds to discourage the moles from reusing the tunnels.
Spray or sprinkle the repellent over the collapsed tunnels and entrances, and in areas suffering from foraging damage from the moles.
Reapply the repellent and collapse new tunnels daily until the moles quit coming into your yard. The repellent usually works within one day, but persistent moles may continue to try new tunnels for a few days before giving up.