Root Bound

Alright so i have a PPP (unknown sex) in the famous red plastic cup we use for our drinks. Now the cup is only half full of dirt cuz i spilt sum as i was planting it. But now its been ooo like 3 weeks and its still only about 2 inches tall. but its got about 8 sets of leaves. Im pretty sure this means it is root bound cuz its going out and not up.

I replanted just recently into a good container, but curious as to what could happen if you let a plant do this (get bushy at youth) then transplant it when it cant take it nemore. Would it maybe make it larger in the end? or just too much stress. thanks!

btw i am using miracle gro(it was free 20lbs) and using 18/6 light (3 42w cfls)

ive seen plants germinated to harvet in a red cup.. buddy got an oz per plant with no traing or topping(they were 3-4 feet high)... root bound is more of a myth.. dont get me wrong, the more root space u have the bigger ur plant will get but dont think it wont grow cuz its root bound... takes alot to do so.. buddy still had lotsa room for roots

hmm i wonder what it could be then. its only half full of dirt though. so i had to cut the cup in half cuz its so bushy. but my other ones filled out just fine. i can see the roots trying to come up the sides now so it really looks like they are trying to find more room. i wont give it nutes or anything still yet, btw quick Q... miracle grow says it provides nutes in the soil for upto 3 months, would i not want to use my nutes until they r gone? i was told (by local plant nursery) if you flush just the soil several times (dry then flush) then leave it outside in the sun for a day the nutes will be washed out. but idk for sure

ya if u flush it out several times they can wash away... and ya ide hold up on nutes for a bit...

size of plants is useually predetermined by its genetics keep in mind what works for one specimen may not for another know what u r growing and going from there is your best ally in growing

Rootbinding is not a myth, but it isn't dangerous. All it does is stunts the growth unless you move it into a bigger plot, then it will grow as normal. Plants do generally alternate growing up, out, thickening stem, focusing energy to different places at different times. Don't worry yourself.

no such thing as root bound