Growing in a rock Bonsai style
In this style the roots of the tree are growing in the cracks and holes of the rock.
This means that there is not much room for the roots to develop and absorb nutrients. Trees growing in rocks will never look really healthy, thus it should be visible that the tree has to struggle to survive. It is important to fertilize and water this style often, because there is not much space available to store water and nutrients. The rock in which the Bonsai grows is often placed in a very shallow pot, which is sometimes filled with water of very fine stones.