Q.Pruning Etc. Zone 3 Grapes
I live in Libby MT (about 2000′ elev) – have 3 grape plants. I have 6 raised beds 4’x18′, 2.5’deep, with stockfence trellis connecting the ends, imbedded about 15″ from end of bed. center of trellis’s are about 6′ above ground level. Each grape is planted on outside edge of trellis about midway – giving a 2′ space in all directions.A Somerset Seedless planted spring of 2019 – doing well (even has 1 small cluster of small grapes, now turned red). 2 others purchased from an ID man at a local farmer’s market. One was a type of Concord, not sure about the other. I think the Concord is doing the best, vines about 5′, the other is struggling (but it was initially planted adjacent to a bed of mint – now removed). We’ve had 3 nights about 27′, about 1/2 of the leaves are now brown. What do you recommend for winter protection & how should I prune them? I’ll attach a picture of my garden. Trellis are in center tho not very visible.

Certified GKH Gardening Expert
The most important factor will be cold hardiness. It would seem that you have grapes that are fully hardy in your area.
Outside of this, proper care is the best method for ensuring that you get a nice crop of grapes. These articles will help:
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-5/zone-5-grape-varieties.htm
https://www.gardeningknowhow.com/edible/fruits/grapes/growing-grapevines.htm
https://www.gardeningknowhow.com/edible/fruits/grapes/prune-grape-vine.htm