My favorite way of wintering roses is to make a cage out of chicken wire with about 9" or more space between it and the rose. Stake it in lightly so it won't blow or shift. Mound about 6+ inches (up above the graft in your case, mine are all "own root") of compost, then FILL the cage with leaves, packed a bit, but not too much - weather and snow'll do that, and you do need a little air in there for insulation. I get some burn off but this really seems to protect the roots and should protect your grafts.

-Marie

Rose growing and Minnesota is a lot of trial and error for each of us- I've killed more than have lived but I'm stubborn (or stupid). I planted tender hybrid teas (15)last year and asked a similar question to yours..Jan (Dentaybow)posted a link for the Far North forum and some of their methods of rose protection. I tried one that amounted to planting the bud union 4 inches below soil level- then in the fall mound with 18 inches of soil and cover with another foot or so of mulch and cover with a tarp for winter. The key was that the whole entire bed was done this way, amounting to more than 2 feet of protective covering and complete surrounding for the roses in the center of the bed. I used raked leaves.I planned the bed to be rose-only with winter protection in mind. They all had dieback but only 3 died- some on the outside were "one-cane wonders" until I took mercy and shovel pruned them. I have Mordens and other hardy roses that I didn't do anything to- some years they dieback to the soil but then send up new shoots, don't be too hasty in writing them off in the spring. The climbing Blaze? I would wrap in burlap and bend them over and cover with some kind of mulch in my yard but like I said, it's trial and error...and hard work, sigh.

i have knockout roses in barrel planters ,do i need to cut them back? will they survive in a planter?i live in tenn.

I don't have any knockout roses- a few years back I had hardy roses in planters which I threw into an unheated shed and did nothing else and they survived just fine- pruned them in the spring and they up and grew like normal.
This is really the time of year that I regret having roses- now the big debate starts in my head..what should I do with them this year, how much do I want to fuss, which ones can't I live with out yada yada yada. Fifteen of them- four feet tall and healthy waving at me everytime I go outside......

Morden roses are very hardy. Even so, with those and the candian explorer named climing shrubs, I alway put a good pile of soil on the crown.
I put in 2 climbers this yr...ramblin' reds. I will take the same precaution with them as the other ones. It seems to be worth effort. The Red did great for growth but were a disappointment with the quick fade of the bright red for which they were planted for.

One thing to think about is that covering roses with mulch to early is a commen problem. The mulch should be put on AFTER there is a good chance that the weather (and ground) will STAY cold. It is hard waiting until it is cold enough, especially hard on the gardeners working in to cold weather, but you will have better luck with survival rates for your roses.