I have one hps 1000 watt I think (I'm new to growing) 17 inches away from my flowering cheese and 707 plants...both are in the second week of flowering. 2-27-13 (tomorrow) is the start of the third week.
As close as possible while keeping all your plants in your lights foot print . General rule of thumb is put the back of your hand to the light where your plant is/ would be. If it feels too hot your plant won't like it
