Size of pot

Depends mainly if you’re running autos or photos. This might be the only time I’d recommend autos. Unless you wanna wait til late summer to harvest photos. If you don’t mind splurging on soil - I’d go 10 gallon autos (lowest 5 gallon) Or For photos I’d be doing 25-100 gallons Don’t do in the same pot unless you’re doing like a long rectangular raised bed.

After looking back over your dimensions am I reading that correctly 38' long, 14' wide, 5.5' tall? If that is correct I would think about possibly tilling the dirt with compost and amendments and just growing from the ground. 5.5 feet shrinks quickly especially when you add over a foot of height from the pot. Also takes sativas out of the running as they tent to grow tall and stretch, would require constant training from mid veg to mid flower.

Both answers are great! Covered everything I was going to say.

Congrats on your first grow. I would say the bigger the pot the better. The root base of the plant will be one of the main factors on how big the plant gets. bigger plants eat, drink and yield more. Once the plant gets so big, its need of the real-estate in the pot will become higher. this will become more evident when its in flower and when its hot out, feeding and watering will become tricky especially as some plants feed differently and the medium will become dry and depleted faster. not to say you can't plant multiple plants in one pot, just be ready for surprises if you do and its not big enough. IMO autoflower min pot size 1gal - max pot size 10gal - does NOT take well transplanting. photoperiod min pot size 3gal - max pot size 50gal - takes well to transplanting. I grow in 3-5 gal pots in doors for all varieties, I like how compact it keeps the plants in the tent. Outdoors though, I'd aim for around 8gal for autos. and 30gal for photos or grow them in the earth. best of luck

From what I have seen you do not really want multiple plants in the same pot, they end up competing for resources, and they will end up shading eachother and when they bush up will cause airflow issues and possible rot/mold issues. Pot size really depends on how big you want plant to be. Also depends on if you are using fabric vs plastic as the air pruning of fabric allows a bigger plant to grow/a plant to grow longer without root bind. I generally plan a gallon per foot, but that also depends on strain and training I have planned.. some grow in 5 gallon buckets others 100 gallon bag