Listerine is a household name when it comes to mouthwash. There is some evidence that Listerine may have uses outside the home as well. From insect control to killing weeds or even disinfecting pruning wounds, Listerine may actually help plants -- and certainly will not harm them.
Listerine contains "four essential oils," as the makers, Johnson & Johnson, explain. These are eucalyptol, menthol, methyl salicylate and thymol. Together they form an antibacterial solution that works in the human mouth -- and possibly on plants as well. In addition, menthol, and especially eucalyptol, seem to work as natural insect repellents.
Listerine on Plants
There is no evidence that the ingredients in Listerine are toxic to plants -- and tremendous anecdotal information to suggest that it may actually prove helpful. In fact, orchid and rose growing experts and other master gardeners sometimes actually suggest using Listerine solutions on plants, although take care to ensure that you don't burn the foliage of your particular plants.
Listerine's Uses in the Garden
Listerine may discourage insects on your plants when sprayed on, either at half strength or in a mixture with water, soap and sometimes even soaked tobacco. Full strength, Listerine disinfects pruning equipment and treats plants for bacterial infections. Listerine may repel animals from your garden and even keep the mosquitoes off you as you enjoy it.