A dying bonsai plant can be saved. Pay close attention to its symptoms. The most common cause of bonsai death is incorrect watering. Watering too much or not enough can cause loss of vigor, yellowing or wilted foliage and branch shrinkage. A few simple steps can help revive the bonsai.
Remove the bonsai tree from its potting container and trim its roots. Use sharp shears or scissors that have been sterilized with wood alcohol. Trim away any black or decaying roots. Infected roots will appear black, while healthy roots appear brown, similar to the trunk's color. Do not remove any healthy roots.
Prune away the dead and wilted foliage, stems and branches. Make sure you sterilize your pruning shears to avoid spreading bacteria or disease to healthy parts of the tree. Prune only the unhealthy parts.
Re-pot your bonsai in a fresh container that is slightly larger than the original container. Before adding soil to the container, sterilize the container with a small amount of wood alcohol. Allow the container to air dry completely before re-potting your bonsai. Make sure the bonsai has new soil. Use a quality potting soil that includes low phosphorous, potassium and low levels of nitrogen. Bonsai trees prefer sandy loams, so mix sand in the potting soil.
Make sure your bonsai has direct sunlight for at least 6 hours each day. Keep the room at a moderate temperature if the tree is kept indoors. Your bonsai uses a combination of sunlight and water to produce nutrients. If the bonsai does not have access to these basic necessities, poor health is sure to follow.
Water your bonsai lightly. Start with a half cup of water applied around the roots. Because over watering could be the cause of your tree's poor health, slowly increase its water intake. Check the soil's moisture daily. If the soil feels dry, your tree needs water. If the soil feels moist, do not water. If you find that the tree requires water daily and is showing signs of revival, increase the amount of water you give it and reduce the number of days each week that you water.