For an 8x8 I would use 4 , 400watt lights. One over each 4x4 space I think that would be an awesome set up myself, I'm just starting to learn about cobs but if your going to go led read read read watch videos read some more and make a diy light but for an 8x8 it a going to cost an arm and a leg.
Also in my experience from seeing noobs on here it's best to actually listen to what experienced people are saying and at least concider what there saying to be truthful. And research it...
Heat has nothing to do with flowering I mean ideal temps make for ideal flowering but in Canada where I'm from they flower outside and we have frosty mornings in late season and they still flower just fine...
I'm not to worried about the lower stuff I know there could have been potentially 5g on the bottom of each plant of popcorns. But I'd rather keep it tidy and prevent mold.
There's 9 under a 400watt mh I did accidently strip a part of the bark. They are up for a transplant soon outta there 1...
I also removed a bunch of the insides of the plants these are growing nothing like there mothers that I grew from seed. way bushier and have random single leaf sets.
I'm a stripper. I like to strip the bottoms of my plants lol, these white widow clones are crazy bushy and the bottoms were just a mess of small branches so I stripped them. who else does this?
Before and after
It was about 2 weeks from being done just the weather didn't agree with this plant so I wanted to try the strain indoors. And I seen roots in 2 weeks and new growth in about a month! 6 of the clones survived out of 15.
Took this of the bottom of on of my green crack plants late in flower it wasn't very healthy but that was just shitty damp weather. Anyway it's revegging and I'm stoked.
I just use 1 gallon of medium to .5 gallon of perlite. Its really your own preference. You don't even technically need perlite it definitely helps though!
I've grown them from cropking for 2 years and they do stretch a bit, they always go moldy on me(outside) so I'm not growing them again but they grow beautifully.