Trailers are a bit new to me. I have 5 mini, semi's in my recently exploded collection. (The last thing I clearly remember is 5 or 6 total .... now I think I've crossed the 50 threshold! NO more room, what with the orchids back inside!) I would like to put some of the trailers in bonsai pots. How do you determine the size pot for a trailer? Still the 3:1 rule? The biggest is Rob's Humpty Doo. It looks fine in the cache pot (attached) but a bit floppy otherwise.

Any suggestions?