A quick tip if you're looking to remove stubborn stains from your plant leaves. You can do so by using a mixture of milk and vinegar or lemon juice, according to The Kitchn. It's a pretty simple recipe, all you need is milk and vinegar. Pour 1/2 cup of milk into a bowl, then add 4 teaspoons of white vinegar and mix. Let the leaves soak in this mixture for at least 10 minutes, and then rinse off the solution. Repeat this process until you no longer see the stain, and your leaves should be as clean as new.