Eventually... just get a real pot or a plastic bucket of sorts. i wouldnt use a metal container, someone will come along and tell you why im sure. I just dont remeber why not ATM
Roots stop growing when they reach air. They will go through the holes a little, but as Jog said, just get a real pot for like $1.65 at any garden center or Home Depot.
Gotta correct you there Prophessor, Roots do not stop growing when they hit air, they redirect. its why you drill holes in the sides of pot to help prevent root bounding. they hit the air pocket then grow away from it back towards the center of the pot