Bonsai trees need “free-draining” soil, because their roots can’t stand to be wet all the time. Bonsai soil is the perfect solution as it allows the water to drain freely, but it still retains moisture well. This type of soil also lets the roots breathe and it prevents compaction. The type of Bonsai soil you choose will be determined by the type of tree it is. For example a conifer tree will need a conifer mix, while a tropical tree will need a tropical mix. Make sure all drainage holes are covered with screening before adding soil as this will help prevent the soil from washing away. Only use dry soil when you are repotting.