Need help with experiment

ok say i wanted to start growing in them beer pong cups tht you get from your local store(the cheap plastic red ones), and im starting them in soil, indoors, under 400w HM/hps dual ballast. how many could i have growing at once just under the 400w lamp before it gets be to crowded?? and what type of soil should i use to have them vegging in?? i planned on keeping them in separate cups till i need to change them either into individual plastic flower pots, or in to the ground(holes dug at least 3' dep 6-5' wide. idk
can someone help me????

You can grow about 4-6 plants to full size under a 400w without them getting too crowded, it depends on the type of reflector used, and also if you plan on topping/LST or other techniques that helps plants bush out. But if you are only using the 400w for veg, you could probably fit 10-12 seedlings or clones in plastic cups under it.

it kinda depends on your grow area
you could have a good 4-6 in there, then another few out on the sides that would only grow sum little nugs, but still good for food etc etc

hell yea thanx man

dose it matter wheather or not if put them in individual containers or i put them in the ground dont want to drop them in the ground if they grow better in pots! ya kno