Bonsai is an art form that requires years of training and centuries of dedication. At the 2012 international bonsai convention, a tree was on sale for 100 million yen, just under a million dollars.

Q: We have a large tree-form lilac that needs to be trimmed back quite significantly. I can’t trim very far before I cut off a lot of leaves. What’s the best way to do this? Should I be concerned that ...