My first outdoor grow (had no idea what I was doing) I had 3 coco plants in 3.25g pots all coco, started vegging I think around April under a t5 indoors outdoors by may. By harvest they were 5ft high by 4ft wide super silver haze btw had to water 4-5 times a day to keep em from drying out also had the pots surrounded by 2 cinder blocks on all sides to keep from falling over, they were pretty much like sails at that point, and they still fell over probably 6+ times during the grow.
They got a lil over 1 lb each very high yielding pheno tho
It's def possible but now I do indoor trees in 15g
smart pots of chow mix it's great, the pot is solid roots by harvest, but I've been considering scaling down the pots to 10g due to drip rings not getting the whole pot and having some salt build up on the sides, before i do that tho I'm going to fix my drip rings lol
I also know Janus grew 2lb trees in 5g pots w/ all perlite look up Janus treatise on growing its great info