So weed can grow outdoors...some of the monsters that I've seen pics of online are truly something to behold...they're like trees... (if anyone has a pic of a root system for one of these, I'd be interested), when left to their own devices what the Earth gives them is remarkable. Obviously some of these I've seen will have used soil mixes, fertilizers and the like. So what I've wondered is, is there a method that's kind of half way between? Say if you grew under lights, but in "dirt"? If you were to say, use a quality store bought "potting mix" that said it would like "feed your plants for 6 months" or what have you - would that be enough? Would this kind of mix be applicable in this situation? I don't have any plans on doing this myself...but I have often wondered if one could do it on the comparatively "cheap and easy", but just, indoors.
Outdoor plants planted directly in the ground (as opposed to in pots) have virtually limitless space to spread their roots which is probably the biggest factor in allowing them to grow so large. It's not really that the soil is anything special. You can grow organic by having the right soil that contains the nutes in it rather than using the kind you mix with the water. Most indoor growers do plant in pots with soil, the alternative is hydroponics. You can still get big plants indoors if you use big pots. But for obvious reasons most people don't actually want particularly tall plants indoors. It's common actually to use techniques like scrog to prevent plants from growing as tall so light can penetrate the canopy better and get fatter nugs.
Soil works fine indoors, but generally speaking, its a bit slower and less productive than hydro. IMO it is easier to get a bumper crop from hydro because it less of an art than soil culture.
these are soil grown, I've collected dirt from a number of friends who grow and I've been leaving it sit in a pile outside for almost 2 years now, I've flushed it with my hose a couple times while turning it and just let nature do its thing so called cleaning it out, I've found all kinds of crazy things in it while potting plants, worms, spiders, the good kinds. Bugs of all kinds. I've never had any issues with it other then fungus gnats. And there easy to get rid of. Just have to start feedings at a low dose early is all due to any time release nutes being flushed out.