Moss for Bonsai Trees
Moss is traditionally used to add a dimension to bonsai, which helps with the overall visual illusion. Moss is added to the soil surface to give the illusion of grass, plants, and such growing in scale under the bonsai tree. For people buying bonsai trees, the presence of moss is always a good sign. There are a great number of types of mosses and lichens and these can be mixed to provide a very effective result overall.
A little known fact about mosses is that they leech minerals into the soil when watered. This benefit however is often negated by the fact that moss, if allowed, will make a shield on the surface that water will not penetrate. When not used for 'conservation' purposes, they should be planted sparingly so that their effect is natural, and they do not prevent water from reaching the soil.
Along with the growth of a healthy crop of moss often comes the appearance of a silver fungus around the soil line at the trunk of the tree. This is a sign of a healthily growing bonsai tree. The fungus develops as the moss takes hold, and it cannot be artificially implanted. In the heat of summer, moss may turn brown. This is not a bad thing, as it means the bonsai tree is getting the water it needs. As soon as cooler temperatures and higher humidity return, so will the 'green velvet' that is most commonly associated with moss under bonsai trees.