I think you're right, alfonso, that lots of people with PPL do not actually grow. It's like most things. Looks easy until you try it, and then you have to decide whether it's worth the hassle. Even with being legal, the question arises. You have to hide it to some degree, like when visitors come, or the furnace guy has to go upstairs. Not that it is shame, but not a good idea to let too much word of knowledge creep out into the world. So there is worry on top of expense. Probably lots of people try growing but don't pursue it long enough to learn how to do it right, get the right equiepment, make plenty of room for it in the house, etc.