I've never had UV lighting. The local reptile store staff ensured me it wasn't necessary for the garters, but for my own peace of mind, I keep the tanks on the side of the room where the late afternoon sun shines for a couple hours. (not directly in front of the window of course!!)
Don't know if it makes an iota of difference to the snakes, but I like to think they enjoy the little sunbath every day!
