Full size standard tree roses

The recommended method to winterize in my zone 5 area where it gets to -20 degrees is to dig a trench on one side of it big enough to lay the tree roses over and bury it. After you get the trench dug, you dig in on the side opposite the trench and cut the roots so you can lay the tree over. That way half of the roots are still in the ground. Don't cut the roots too short.

It will look like a little grave when you are thru. Bury the tree rose at least 12 inches deep. AFTER the ground freezes cover the whole thing with 6-8 inches of shredded leaves. In th spring when the Forsythia bloom dig it up, prune the top back, removing all the dead wood. Try to leave about 12" of cane after you prune but remember, the shorter you prune, the bushier your tree rose will be. If you leave the canes too long the bush will be kind of gangly. The weakest part on a tree rose is the bud union. Unlike a regular rose, that bud union is exposed and if frozen too severely the differing tissues will separate, killing it. You can prune some this fall to make it easier to bury it but don't cut off any more than necessary. Remember, this spring you can cut off more but you can't put it back on. I advocate spring pruning only.

Another method that may work but requires you to watch it closely is to move it into an unheated garage, if it's planted in a pot. If not, then that rules that out.

A local rose society or Consulting Rosarian near you can tell you better how much winter care you need to use.