I have never tried them from seeds. I know if you cut a stem and put it in water it will root. I grow mine in pots and I leave them in the pots and bring them inside for the winter and they come back.
I have been told that there are little bulbs/potatoes that people take out and store them like dahlia bulbs. I could not find any at the end of summer so I just save them through the winter in the pots.
