If you're growing in super soil, you'll need to keep that in mind when choosing the size of a pot to utilize. Sohum at least had a chart for that, based on time in veg and time flowering. In general, bigger is better as that means more microbes and such in the soil to make nutrients for your plant.
I can tell you from personal experience that you're gonna be in veg for a long time to fill out a 4x4 with a single plant. My original plan was to just grow 2 plants in my 2.5x2.5, but I ended up upgrading to a 4x4 and I got tired of waiting on 2 to fill out the space and just flipped so I could open it up for my next run of 5 plants.
If you're not constrained by legality, you'd probably be happier growing more plants in that space.
SoHum Living Soils® Best Practices SoHum Living Soils® is a microbial-based super soil that has been scientifically developed to simply provide the easiest and most cost-efficient means to cultivate premiere cannabis flower. SoHum’s robust microbial content
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