transplant

hello rollitup I had question about transplanting recently I used a plastic cup for my seedling sprouted from this 12 oz bottle that I cut in half, than yesterday I saw roots hittin bottom of the cup so I just grabbed a razor and cut the very bottom off will that work? Than I put it in 1 gallon.. I thought it would work because I always heard roots grow downs ward but my friend told me it can get rootbound how I did it

Did you just cut off the bottom and leave the sides, so the roots can only grow downward? If so, that's your big mistake. You need to TOTALLY transplant it. Get rid of all the plastic so that it is nothing but the plant going into the new container. Sorry if my reply sounds sort of ignorant, but the way your post was worded, that's what it sounds like you did. And a one gallon container isn't nearly big enough to grow a plant of any size. Get at least a 3 gallon pot so the roots have room to grow.