This was a simple transfer from shallow pot to slab for a Chinese Elm .With the chosen slab i made a mix of clay , sand , moss and composted cedar needles {muck} to build a small barrier around the perimeter of the slab . The mix should be moist and sticky enough to adhere to the rock . Build the wall up to produce a saucer effect to hold the potting mix and to assist in water retention and to give the finished landscape some depth . If the slab has a concave base a drill hole may be required for drainage , simply drill a hole with a masonary drill {dont use rotary hammer} and simply place a piece of mess over the hole .
With the slab prepared sprinkle a small amount of bonsai mix into the base and around the perimeter, place the tree in the desired position and pot up as per normal tray . When back filling press the mix into the clay muck wall to blend into the finished landscape , and prevent water from washing away the wall . Using a small stick push a channel through the wall to breach the barrier to aid drainage . 
Depending on the size of the tree wire may be required to hold it in position . Loop a wire up through the drain hole and secure . If the slab doesn’t have a drain hole place 2 wires over the root-ball , prior to back filling and secure by folding over the edge of the slab and crimping with pliers . Another method is to wind hemp string several times around the slab , over the roots and secure, this will rot in a matter of months.
With the tree secure and soil in place , simply place rocks and moss to achieve desired effect .
