British Columbia is your tree fern hotspot, especially on and around Vancouver Island. That's the maritime climate for you. Nearby Salt Spring Island hosts the nursery that all the fernies talk about (Thimble Farm). As to how hardy those local tree ferns you've noticed will be...well, not at all, you're not even close - it's far too cold in January where you are. A heated indoor winter berth would be essential. If the species being sold is Dicksonia squarrosa, from New Zealand, then you could just about overwinter a tub specimen in your home in a bright spot, if you paid close attention to keeping it permanently damp. But not the more likely Dicksonia antarctica, from Australia - that one won't cope with indoor home life, though it's considerably more cold tolerant outdoors than any of the others provided winter lows don't don't drop below -10C. Maybe you need to properly identify what your retailer is actually selling before taking this any further...?