Ratio of Peppermint Oil to Water for Repelling Mice
Combine two teaspoons of peppermint oil with one cup of water and then add a few drops of dish detergent to help the ingredients mix better. Shake it all together in a spray bottle and apply the mixture any place that you have or suspect you have mice. Reapply the spray as the scent fades, usually after about two weeks. Also you can put undiluted peppermint oil on a cotton ball and place where you suspect mice.