Is it 1 sqaure foot, tell me more about how all pots are made exactly the same and uniform in every dimension, everywhere, Jekyll. My 5 gal super root airpot that may hold true. My 5gal smartpots are over a ft wide. So what kind of 5 gal pot is he using Dr Jekyll? You seem to have the witty response without knowing all the info. But please go on giving him snide remarks without knowing exactly what he's using. 5 gal buckets like a home depot bucket are over a foot wide at the mouth and when including the flare out edge prob another half inch. So unles you know yhe pot he's using keep the snide comments to a minimum and offer something constructive. Im not gonna clog up his thread, if you're not smart enough to understand what I wrote, a response isn't warranted. I didn't tell him how many he can use because I don't know his pot type, just like you don't. But, being a faux-expert, your condescending 2nd response offered him no help, and showed you didn't take everything into account when you opened your mouth. Because if I was telling him how many pots to fit. It'd be 4-8 plants in 5-7gal pots with room to train for good canopy and light penetration. But you do you Dr.
Id get a Magnum XXXL hood or equivalent to spread your light OP. Lumens, you're perfect withr that light, they flower a 5x5 well. Your canopy control is gonna be paramount though. With that many plants, they'll be a few that will outgrow and shade the rest furthering the problem, so super crop and etc where need be. Scrog it, do what ya gotta. You don't wanna have to raisr your light for the tall plants and lose some light by the time it makes it to the short ones, and they arent getting very strong light, and what light does reach them is in patches shades byt he bigger plants.