one question: if the roots are mearly a vehicle to transport nutrients and water, at what point is the pot too small? at what limit does it get rootbound? you can't have a tree in a bucket, can you?
it took 5 weeks for the majority of my 18 seedlings to get rootbound in 16 ounce cups, at 6 inches tall. how are your plants fine in 1/2 gllon pots, at 18" height?
My plants were in 500ml containers. That's an 1/8 gallon pots.
Plants also get root bound... although I believe natmoon's term would describe the situation best... pot bound.
If you were to repot the plants after this occurs then the roots would have difficulty moving into the new space. The roots would still be capable of uptaking nutrients.
I did get less per plant, slightly... but I believe this was more down to the thrips, and squeezing in more plants. I usually only grow four under 1 light.
Squeezing in more plants allows less light for side branches, so they don't grow as healthily. Also, during veg'... I was a little confused (being a stoner) as to what i was doing myself, and treated it like a SOG grow. The good thing this did was give me plenty of background plants, which provided me with plenty of oil and a chance to study the root development.
I first got onto this through a combination of things, the first thing was on a DWC grow I did, I allowed the roots to become exposed to light for long periods, and they rotted and died. In fact quite a substantial part of the roots disappeared (with help from cannazym) and the plant above remained almost perfectly healthy, and i could still bring it through for a decent yield after now covering the roots from all light. Honestly, it was like the plant above didn't even notice. The other thing was fdd's tree in the ground... the way the roots seemed to just shoot straight outwards... and of course his immense outdoor plants/trees in relatively tiny pots.
I've used way less medium and less nutrients for a better yield.
Great job!! You making lots of oil for x-mas then?? I know you like ya oil 
