250hps, you could run 3 atleast like I said earlier some where on this forum. Im running 2 mothers and a clone under a 250hps watt light and the mother I am about to start the 12/12 cycle on, her stem is about 1cm diameter. If you had a 250w hps and a 120watt light and ran them together in a room, your buds should turn out to be bigger depending on the density of the room and such and if you have a fan going on the plants to keep them cooled.