Almost immediately after I started doing bonsai, I was introduced to show prep. My first teacher was preparing more than 15 trees for an annual show and put me to work adding moss to a saikei (planted landscape). Years later as a bonsai enthusiast, I was doing the same type of work to my own trees. My decisions on what trees to show and when are driven each year by the success and failure involved in growing my trees into top condition. When a tree really starts to look great I start to think about showing it. The road to that point can be long, somewhat like a marathon. In the final year leading to it being ready to show, the tree will typically take much more time and effort than it had previously.
Show prep starts with the decision to show a tree. From there, the focus is on styling the tree - wiring, fine branch setting, and trimming. If the styling comes out well - and the tree doesn't need to fill in again - then it’s getting close to ready. The next major hurdle is finding an appropriate container and getting the tree to fit into it. The last step is to "spit shine, shoe polish," and moss the tree - apply moss and clean up any remaining issues. Then get ready to enjoy the results of your hard work - it's quite an experience to see your tree on display in a show!
After repotting the tree, fill the pot with soil. When preparing to moss it a few weeks, remove enough of the top soil to make room for the moss. Adding a small amount of shredded sphagnum moss will help keep sand, mud, and debris from the moss from filtering into the bonsai soil below.
Applying the moss is a mixture of rote application and a bit of artistry. Fitting it between the roots can accentuate parts of the nebari while hiding other minor problems.