limited hop garden space

I have 5 varietys of hops spaced about 5 ft apart. I know that they are to close but this is just 2nd year. I keep reading different posts about putting a barrel around each to keep from spreading. How big of a barrel? Will plastic work? Plan on moving in spring to give each plant more room but want to do what is needed to control roots from speading all over, and so I can tell 1 variety from the other. Forgive the spelling drinking.

I don't know that 5 ft apart is needed. Mine are on 2ft centers and have had know problems!

Five feet is enough to keep varieties separate, so don't worry about that. As far as controlling roots goes, any barrier that goes down 4-6" is enough. It's the surface roots that are the problem.