Rawbo, if you're looking to grow 4-5' plants indoors then you are gonna need LOTS of space, you gotta allow them room to bush out otherwise it's gonna be tight in there, especially if you don't run a system that has an easily accessible control bucket to add your nutes / fresh H2O. As Canna said, you would be better off growing 4 plants in a 4x4 tent and if you scrog em out you could simply do two. If you're really looking to do more than 4 large plants I would recommend a 4x8 tent. Ideally you would have a 4x4 tent for veg and then a 4x8 tent for flower. Hope you have a large grow area picked out! All this being said, if this is your first time growing, you might want to scale it back a bit. I know it's easy to get wrapped up in thinking about huge buds and massive yields but as hardy as cannabis plants are, it's also extremely easy to mess up a grow, especially when you have more than just a few plants. My suggestion would be to start modest, find a strain you really like and go with it. Start off with four plants and veg em out, when you transfer them into your flowering room take as many clones as you need and continue veggin those clones till your flowering tent is open for the next batch. As you get to know the strain, what it likes as well as dislikes, and you think you've got it dialed in properly so you're getting the most outta each harvest, then would be the time to bump it up and start producing more. My first time I grew 1 autoflower Bubblicious from Nirvana seeds, I didn't have a constant read meter and was just using general hydroponics 3-part nutes. It finished but boy did I have issues along the way. Anyone can grow cannabis, but it takes careful preparation and a watchful eye to get connoisseur bud. Anyway, I hope this helps, you can check out my grow "girl scout cookies rdwc scrog grow" to see how I setup my system (I'm running only two plants in a 4x4 tent and they gonna be monsters!) I only run one tent as I don't have the space to do two but maybe it'll give you some ideas! Good luck!