All you have to do is get a toy or something in Park Projects, then put it close to the chibi-house. Then, on when the forecast calls for smoglings or smogleblobs, just go and play on the thing you got from the PP. *Note: This will not prevent smogglings/ smoggleblobs from doing anything if they're already out. This secret only prevents them from coming out. Otherwise, they'll destroy your flowers. :p