What if I need to stay in Canada for a long period of time, say 3 to 5 months, I have a US GreenCard, do I need a visa then? When I came into Canada they asked me how long I was staying & I told them 3 days & they put all that information into their system because I had flown on a 1-way ticket to Buffalo. Now I'm planning on staying a bit longer because of some business opportunities. Should I go ahead and stay longer or should I leave & come back coz I dont want to be denied entry next time because I stayed longer than I said I would.