Neem oil is your plants' best friend and the number one essential item to have if you want to keep them healthy and vibrant. It acts as a natural insecticide and increases plant immunity, all while being safe to humans and pets. How to use? Mix 1 tablespoon of Castile soap or any solvent with 1 tablespoon of Neem oil in one liter of water and spray heavily on your plant and soil. If your plant is infected, repeat the process again once every week for three weeks even if the infection has disappeared.