This made me think if there would be some substance where the roots could grow like on rock wool, but that could then be dissolved later. This way you could make a dense root ball and then spread it around to be more flat and once that would grow down, the roots could at least theoretically get real big, plus you could bury it as normal in soil without having to fear too much moisture uptake on the rock wool(or what ever you used).
Its funny you started talking about sharing root system, but having something to block it. This has been something i have experimented on a bit, but havent done any proper research on. However i have been thinking of the sort of system for a while where you would have a large and deep container, which would have proper super soil in it, worms living in etc, so that this part would largely be able to sustain itself with just occasional added food and something like sensizym to brake down the old and dead roots and turn them to food for microbes.
Then in that container you would have smaller pots inserted on top of it very densely, but with no bottom on them. So that the plants can grow inside that smaller pot at first and then start tpo spread out the roots in the large container. This would be for eliminating the competition for root space in early stages. Also you would change the soil inside the individual smaller pots every grow and keep it veg friendly, while the bottom part would be hotter soil more suitable for blooming. You could also add some extra nutes to single plants if just one has some deficiency, by giving it less of a stronger solution that wouldnt leak too much on the bottom part.
This sort of container for example sized 80 x 80 cm and 50cm high with 16 of smaller 20 x 20 cm square pots would be so awesome. Definitely will try it some day if ill have a chance.
