Bonsai Drainage Mesh – Bonsai Warehouse stocks a large range of Bonsai Drainage Mesh for all Bonsai Tree and Bonsai Pot Sizes. Bonsai Drainage Mesh is used to cover the holes in the bottom of your Bonsai Pot to prevent your Bonsai Soil from being washed away when watering, while still allowing your Pots to be free draining.