Overwinter away from hard frost, watch for sucking pests.

Thanks bboy.

I keep them in unheated greenhouse. First surround the plant with bubble wrap and cover the entire plant with three to four translucent/transparent plastic bags.

If the temp goes below -10 deg C then cover with thick paper bags till the temp raises. This is my 5th year with this approach.

Thanks hvp1962. I have moved it into an unheated barn, close to a south facing window. The problem I have had using this barn in the past is that if it is sunny it gets quite warm and I forget to water. The room is insulated, so if it gets really cold, I can put a heater in it. Sounds as though I am using much the same approach as you. Interestingly, I am using my first ripe lemon today, making lemon squares. Taste really good!

I grew one inside for several years in a south facing window. The scent from the blooms was wonderful. If you have a good place for it, consider overwintering it inside.