I think Valiant are considered the hardiest but I don`t know how they would fare in a container. Any chance of planting them in the ground?

I could put them into the raised bed that is about 2-3' lower than deck level, but it would not be true ground level. The raised beds are about 2 1/2' tall, but at least they sit on the ground. This might be better?

king of the north and beta should be hardy enough for zone 3
unfortunately not in pots left in the open

i think burying the pots in the raised bed should work
maybe put the pots in the hole and water the pots in really well,
then when they are good and frozen, cover up with dirt
soon as you can in spring pull them out
and put them in a shaded spot on the north side of your house
this will help premature budding (because pots/raised beds heat-up way before the ground)
and late spring frost killing your new growth

there are a few other options
(all of these begin with watering the plants in well beforehand)

- dig a hole and put your pots in and cover with dirt/leaves etc.
- put in a garage/shed or other protected building (off any concrete floors)
- build a 'room' around them with hay bales and cover the top

i personally do the hole in the ground and cover with mulch/dirt
and have had success even with baby grapes in those red cups for drinking

Last winter (2012/2013) I lost dozens of grapevines (including Valiant) because I left them unprotected in pots. Our winter low was -37C. Previous years I had either piled them up and covered with dirt or put in open trenches (and let the snow fill around them) and never lost more than 10% over winter. In comparison, things that survived last winter in pots with no apparent injury included edible honeysuckle and a female Arctic Beauty kiwi (Kolomikta).

Thanks for all the feedback. I've scrapped the idea of containers on the deck, but my raised beds are at the deck perimeter and I may be able to utilize these. I have good success with lots of perennials surviving in these beds. It's worth a try. The grapes will just have to grow a little taller up the structure.