if you do feed your fig trees make sure you are using something low in nitrogen. Something like (UltraGreen Tomato and Vegetable Food) in early april and again early June with a good source of trace minerals is perfect if not going organic. Using rock phosphate, Wood Ash, Greensand, Alfalfa Meal, and compost with a natural source of trace minerals together works great as an organic and vegan option, but there are many other things you can use as well just remember to keep the N rating low. Also research in the fig community has shown that silica seems to make wood more resistant to winter damage .
Your summers are too short to ripen main crop figs so if you keep losing last years wood you won't ever get figs. I honestly think containers are your best option with you protecting them in winter. The Desert king variety sets huge crops of beba figs early and ripens in cool summer areas. It's not as hardy as Hardy Chicago but if you are willing to take care of it through winter it will probably be your best producing fig tree. In zone 6 hardy chicago can freeze to the ground and still produce a few figs in late August till the first frost but unfortunately I can't see that happening in your area.
