I live in the middle of the USA in Oklahoma. I have to store my bougainvillea in the back of the garage during the winter but we rarely get to 20 degrees below zero here. In Canada, I would think the pot would need extra insulation to survive. Last year I had 3 in a long pot and only the middle one survived this past winter. The two on each end was the insulation the middle one needed to survive. I leave it on the patio until the first freeze causes it to loose most of the leaves, then I cut it back to 7 or 8 inches before storing. Good luck!