Since they take such different shape it is hard to picture it but the below soil portion of a plant is at most times pretty close to being equal in size to the above soil portion of a plant. Just keep that in mind the next time you see a big plant in a small container.
 
Once a plant’s roots begin to circle a pot the plant is then in some degree of stress. The longer the circling is allowed to continue the greater the amount of stress the plant is under.
 
While at times at least to some of us certain strains can seem pretty finicky and a little bit of a challenge at times but in reality the plant is a weed that is very tough and very resilient and it shows that all the time by how well it grows and produces under less than optimal conditions.