Since you are in BC you probably won't have enough light to keep it actively growing.

It will go dormant, dropping most of it's leaves. Keep it dry and don't let it freeze and it should be fine.

In spring move it outside to as much heat and light as possible and increase watering but they are never a keep moist plant. Cutting it back will encourage new growth too.

They are not heavy feeders either.

You can bring in indoors and keep it in the dark, as long as temps are above freezing, and then bring it out again in spring. They are abit slow to get started again until it really does warm up, and at first sign of growth I would suggest fertilizing with a balanced fertilizer. I've found that container plants of Bougainvilla will not bloom as well unless they are well fed, as opposed to those in the ground, which don't typically need feeding to bloom well, and will typically bloom more heavily in the dry season in the wet tropics, all year in deserts, and late spring into late fall here in coastal California, or later if warm enough.

They really do bloom best in containers if placed in your hottest, sunniest spot, and fed regularly in the warm months, stopping in mid August so that they will start to slow down and harden off. A spectacular accent plant as a shrub standard if you can keep it blooming in summer/fall...