Question for Penny in Ontario

Hi Penny - and many thanks you for your recent approach

Just before I went away for a few days holiday a while back - you mentioned that your winter termperatures could fall as low as -45 F (-43C). I have been meaning since to ask you since, what plants survive that? In the UK life for most of us would end at -15C (5F). I am in a cold part of the country and this was a bad year at -10C (14F).

I can understand how you can grow annuals, as they will overwinter as seeds. But what perennials can stand that temperature? What has been your lowest? and do plants survive because they are covered by a layer of snow?