Unlike many people, ferns like a humid environment. To create the conditions they prefer, place the potted plants on a tray filled with water and pebbles. As the water evaporates, it adds moisture to the air around the fern. Any receptacle will do, from a simple plastic saucer to the metal tray we found for this young Boston fern. Pebbles provide a barrier between the water and the plant's roots, as well as a decorative source of color and texture.
Climate Control for Ferns
Martha Stewart Living, February 2006