I'm not sure about optimum, but I keep mine at 40-50% without mold issues.

Just a glass of water won't help, but a large pan of water might if it's warm enough. You can humidify your room putting a tray of water over your ballast, which is always warm, but that's a huge shock risk so I don't recommend it. Last winter I put a tray of water in front of my space heater's blower as a makeshift humidfier. It seemed to work fine.
stinkyattic Reviewed by stinkyattic on . Leaves drying out? Hey all. I'm still doing my "practice grow" with a couple bagseeds before my real seeds arrive. As I am doing this, I have just come across a little problem. It seems as if the leaves of my plant are drying out. They are still vegging, have been for 2 weeks. They are under CFLs. And it seems that they started drying out once I put a fan in my grow space. Now, what can I do to fix this? Can I use a spray bottle and gently mist the leaves? Or what? I don't want to add any more water to Rating: 5