Whatever makes it through tends to depend on the hardiness of the plant and its location. I'm hopeful everything up by the house will be fine because I've covered them, and they are fairly sheltered in that location, and draw some heat off the building. I'm doing laundry every night so the dryer vent can blow warm air over them for half an hour. I'm curious to see what makes it through -4C at night. There's a lot of snow so that might provide some insulation as well. We're getting 10-15 cm today, which is going to result in a lot of broken trees, because most of them are already weighed down with the snow we got yesterday.