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.