i have a rootbound plant

[idontno]

i have a plant that is rootbound in about a 1x1 foot pot(lil bigger) and the plant is only 3 weeks old. i transfered into this pot and it filled up 100%horizontally and vertically with roots 3 days later, at this rate its gonna be in like a 20 gallon pot the roots are starting to grow out of the drainage holes. Its only 3 weeks old and my other strain wasnt rootbound in a 6x6 inch pot for 3 weeks. they were both from seed. this is my 2nd grow and it is 10000% different from my first grow. i heard u can keep it in a 12 inch pot at minimum.. does that mean i can just grow the plant like this untill harvest(right now its 3 weeks from seed)while its rootbound or is it manditory o transplant again cuz i mean it Is a 1x1 foot pot and this would be my 3rd transplant and i dont wanna hurt it

[Jesus]

shit man. what are you feeding that thing? you might wanna transfer it to a slightly bigger container, but then leave it the way it is until harvest time.
what kinda lighting are you using, and are u fertilizing it?

[Canablizz]

I would either plant that thing outside in the dirt, or you coud put it in a garbage pail for the time being, just make sure if you transplant it you do it at nigth when the plant is in it's resting mode so that you dont stress it out all that much.

Good luck on the grow, hope that your not doing all this shit for a male

[Weedguru Higher]

A plant that is underwatered will tend to grow longer roots faster. When they are dry they will stretch out in search of water in the soil. The plants energy to grow will be more focused on its roots for survival than the actual growing. Of course this may not be your problem.
You want to avoid transplanting your plants several times. Its better to go from a small pot directly into one that is way to big. Each transplant causes trauma to the plant, and it takes awhile for them to recuperate.
In your case you must transplant. There is a higher risks because this is your third time transplanting. But by leaving the rootbound it is going to be seriously stunted in grow and overall unhappy. So best bet is to gamble and do the transplant. Just make sure this one is final.
Btw, what light system you got going??