Earl

I think Serrisas need bright light so I would think light only until 11 might produce leggy or anemic plants. They don't need direct sun as much as bright light...south or west windows. And don't forget the humidity...it's as important as the light. My Serrias forest is in a south window right above the kitchen sink. They love it. They flower and get little berries all year long. I still agree with Al...grow lights are worthless on anything but flat leafy plants like African Violets.

Supplemental light is gong to take big time--mercury or halogen, and made specifically for plants. My Halogen I use in the winter embarrases my wife because when you come up the street it looks like a corner street light beaming out of the window. It bounces off the fence 30' away. That's how bright it is. Most people wouldn't want them in the living area of their house. Mine is in a daylight basement right by a very large picture window, south side. I also have a fan running continuously to circulate the air.