How can I protect a Lemon tree over the B.C. winter?

You need to bring it in. It will perish in your winter. Will still need light and water, so best in a south or west facing window.

You could bring it inside for the winter, or up close to your outside wall to keep warm. Also, put mulch around the bottom of the tree to keep soil warm. You could purchase fabric cloth from home improvement store or even Walmart.com. I put a old sheet over mine to protect!

Where exactly in BC are you?

OK, Thanks. Even though you are pretty well at sea level, because you are on a west coast, (and not an east coast such as Comox) you get more rain (or hail or snow) there than other coastal sections of BC. Weather can often change to half way across the Georgia Strait.

So, my advice is on par with others who have said to take the plant in during the winter and keep it beside a window that gets the most sunlight. No promises, but hopefully it will survive the winter, and you won't have to make frozen lemonade as plan B.

You're welcome.