Hi! I have purchased a fairly ridiculous number of dieffenbachia, all of which are now looking sad and pathetic. I am hoping is they will survive living in my office, which doesn't have any windows / exposure to natural light. At the moment I have a floor light on them with a 50W Sylvania brand "Spot-Gro" bulb. Will this be enough? Or am I destined to lose them all? (I am also concerned they have a significant degree of root rot; as it turns out, I had been overwatering them and a few of them are listing and continuing to have yellowing or browning leaves.) Help is greatly appreciated!