So many questions lol

I don’t understand what the point of pruning would be once you move the plant off that middle stand it stops growing. Also, I haven’t been able to move plants back to that stand to grow more once I take it off. And it seems if I leave them there to long they start to die. Also why are there always empty boxes that you can’t open and the bee suggested I read the books laying around but I can’t get any of them to open either.