Peppermint has a pleasant aroma to most humans. However, rats dislike the smell. By planting peppermint trees in the landscape, you can keep rats at a distance. Make a peppermint spray by chopping some mint leaves and adding them to boiling water. Let the mixture steep. Strain the solution into a spray bottle and spray it over areas that are infested by rats. Dip cotton balls in mint oil and leave them wherever you suspect rats, especially around windows and doors. Leave some in the drawers, cupboards, under sofas and other places that are visited by rodents. The peppermint smell tends to dissipate in a few days and thus needs refreshing. In addition to rodents, peppermint also repels fleas, ticks and ants.