The down side is that they can be expensive to install and maintain, but they deep water, therefore providing moisture where it is most needed the roots and create healthy plants. Most plants prefer a humid environment. This is easily accomplished with a mister or a humidity tray. A mister can be obtained from a local nursery or you can use an all-purpose spray bottle as long as it produces a fine cloud of moisture that surrounds the plant and covers both sides of the leaves. Do not mist fuzzy-leafed plants.
Water is added until just below the top of the rocks and the potted plant is placed on top.
Additional water is added as necessary. For orchids the top of the rocks should be about 1 inch from the rim and a screen stretched over the top of the tray the potted orchid will sit atop the wire mesh. My orchid also benefits from a daily misting during the summer months, although this may not be necessary if you live in a naturally humid location. All plants, even those misted daily or on a humidity tray, require regular watering. There are many types of watering cans available, from rusted old aluminum to stylish galvanized tin to colorful plastic cans, those with or without sprinkler heads and even cans with removable sprinkler heads.