I understand you're supposed to harvest from the top and add new boxes to the bottom. Can someone explain to me how this is physically accomplished? Let's say you have 4 boxes, you harvest one and add one to the bottom. How do you get the one on the bottom under the other three and on top of the floor. It seems like it would be hard to do. I'm probably missing something obvious or have made an incorrect assumption - could someone tell me how they do it?