You can hang them on the stems or the whole plant if you want, or you can dice them up if you want. I have a lot of humidity that I have to deal with where I live so I have to trim up all the leaves and then cut all the buds away from the stems and lay them on screens to dry them. I actually use an old refrigerator that I have vented so that it will draw air through it. Some people use closets, and some use the same grow space but turn the lights off so that the buds stay in the dark. But you want them to be in a fairly dry place and as the moisture evaporates into the air, that air needs to be removed so fresh air can come in to evaporate more moisture.