what kinda lights are you talking about...cfl's, metal halide, a stop light u robbed from your town? lol u gotta b more specific.. cuz the range varies between the light that you have... where as if you had cfl's you would want them no more then an inch an a half away ...
im also guessing thats not your plant... cus that plant was either topped or lst'd... they dont just grow like that without an influence.. although it would be nice...