I flower with a 400 watt HPS in an 8 square foot closet.
Roughly 50 watts per square foot. Use MG soil adding perlite and blood and bone meal.
24/0 for veg and 12/12 for flowering. Watering when needed (judging by weight of pot and dryness of soil) Alaskan fish emulsion 5,1,1 veg and Guano 2,10,0 flower