Ive grown with a 400 watt in a 2 bedroom apartment. Your bill will go up about 30-50 bucks. Although a 400 watter is a good place. I would start with fluoros about 10 made into a strip of wood or cardboard for vegging. A 400 watt just waste electricity for the first 2 months. After about a month or 2 throw the 400 up for 2 months and your smoking:jointsmile: