A must-have for indoor gardening, saucers prevent excess water from leaking out of your plant pots. By catching the water in a saucer, less water is wasted because your plants can then take it up through their roots as needed, as opposed to the water simply spilling out and making a mess of your flooring or windowsill. Many gardeners also use saucers outdoors for the same reasons. Water and wet soil can cause damage to outdoor decks and balconies that a saucer would help prevent.