Bonsai trees, like all living things, require water to survive. Watering mistakes are one of the primary reasons bonsai trees fail to thrive. Following a few primary watering principles make this aspect of caring for bonsai trees relatively straightforward. Properly watering your bonsai tree won't guarantee it will thrive, but it increases the odds tremendously.
Soak your bonsai plant in a tub or sink of water. Use enough water to cover the container, the soil and the bottom part of the trunk. Allow the tree to sit in and soak up the water for five to 15 minutes. Remove the tree from the water and allow it to drain.
Give your bonsai tree an occasional shower. Put the bonsai tree in the shower and run a light shower of tepid water on your tree for 10 to 15 minutes. The shower simulates rain and gives the entire tree a nice boost.
Mist your bonsai tree with water. Use a spray bottle and spritz the leaves of the tree with water. This method works best on trees especially prone to root rot; it provides the tree with moisture without allowing the roots to sit in water.