I have 10 planted. I usually feed 4 -6 at a time and funny thing is, sometimes, they won't have the option to feed and then a few sim days or weeks, the option is back. I don't use them all either, in fact in one game I have now, I have quit feeding them, I probably have 50 Dragon Ripple books in the inventory anyway, not sure why I have not sold them, I probably forgot about them. As far as re-feeding, if I choose to re-feed I might for a few days and then quit. I like feeding them life fruit. In my first baby boomer family, I can't quite give them up yet. I have the mother as the ghost in the family and three others have passed away so far out of 10 children.