A grow room is literally the exact opposite conditions for mold to grow. You are actively setting up an environment to grow plants, with fresh air cycling, and a relatively stable climate. Mold and rot happens when left alone, in damp wet stale conditions, under dark corners and behind cold things. Takes a certain kind of special to develop a mold problem in a grow tent, unless bringing in obviously visually healthy mold, spreading it around, spilling water on the floor, killing the fans, and leave it for a few days or weeks.