Pot into a pot

Well my friends and I smoke on the back porch all the time, and if we happen to be breaking the ganja up out there we throw the stems and seeds into my yard. Rain came. And weeds starting growing, then I spotted a very very familiar looking weed.

Jimifer [the plant] needs to be transplanted into a pot, I want to know how deep I should dig so that I don't damage the tap root, of course if any of you could tell me how wide around the plant I should dig that'd be greatly appreciated too :]

here's some pics.




Thanks for all yur help