What you are talking about is called the "Minnesota Tip" here. How it works is that you dig a trench as long as the rose is tall on one side of the rose starting a little ways out form the base of the rose. Then you dig up the opposite side of the root ball so that you can lay the rose down into the trench and then bury it all with soil. You are not bending the canes down but actually lifting the roots on one side to lay the rose down. The roots on the side with the trench will bend much easier than the canes. Like you said the canes will snap if you attempt to bend them down that far. It works but it's a lot of work to do and undo in the spring. Burying the canes can also lead to other problems like cankers so I wouldn't suggest it.

I would suggest that you stake and cover it instead. Put in three or four good sturdy stakes around the rose and then wrap around the stakes a couple of times with burlap and tie it up with twine or staple it to the stakes if they are wooden. Mulch the bottom with what ever mulch you prefer about a good foot deep too. That should be enough protection for the roots and the canes to get them through winter. You will probably still have some winter cane die back but it shouldn't be excessive.

Frankly, Don Juan is not a good choice for your climate. 'Quadra' is a dark red rose that would be self-sufficient as to winter-hardiness and disease resistance.

Good luck, though.

I don't know why you say that, Michael. I know a lot of people who grow DJ just fine in zone 5. I also have several friends in Michigan that ditched Quadra because it was a disease riddled non preformer for them.

Thanks! I will try staking it and wrapping it up with burlap like you suggested. Hopefully that works!

I could not keep Don Juan alive in zone 5 northern Ohio and I do not know of anyone in this area that still has it. Help Me Find lists it as a zone 6b or warmer rose.

I never could keep Don Juan alive through winter either. I tried sdeveral plants and various winter protection methods. On the rare occasion it survived a winter, it grew sparsely the following year and would finally die the 2nd winter. One the occasion it did survive it was riddled with canker and had to be cut back rather severely
Quadra took 4 years to finally perform and now is one of my best blooming climbers. Even now it's covered with flowers. I find it's disease resistant and extremely hardy. It usually requires only a little tip pruning in spring.
It grows very large and requires much pruning to keep in at bay.

Although not as hardy but still enough that it only dies back to 3-4 feet, is Dublin Bay. It's disease resistant for me and has better shaped and a richer red bloom than Quadra.

I don't spray fungicides so disease resistance is an important feature for me.

I had trouble with DJ in zone 7. I had two that died over the winter. Of course, I didn't do any winter protection. But it's a tender rose. But you may as well give it a shot! I love DJ and I keep trying!

Well I guess it must have to do with micro climates then. Or maybe the amount of winter protection your willing to do. But since you already have it and it sounds like you are willing to do protection then perhaps it will do just fine for you.

My 12 year old DJ has survived many tough winters and comes back quite well. He suffers lots of winter die back but rebounds well and gets up to 12-14 feet. Does so well here, I just purchased another. But my tree roses survive also. I must have a mico climate thing going on. Sometimes I wrap with burlap...sometimes I don't.