Question
Zone 5a.  I have a Don Juan rose outdoors in a pot - doing beautifully. Will take indoors before first frost. How far down should I prune before taking indoors for the winter?

Answer
If you have the space, I wouldn't prune Don Juan at all. But if you have to cut it down don't go past 4 feet. The reason for this is because some climbers can revert to growing like a bush if they are pruned back severely. I would prune it just enough to make it through the door! Don Juan can be a difficult rose to grow so if it is doing well for you, you are lucky. I wouldn't take it in before the first frost unless you are putting it into an unheated area. Roses go into dormancy by drawing down the sap to the roots and by hardening off the canes. If you put it in a place where it can't do this, it will continue to put out weak growth which could be killed in the cold.  Leave it outside until the leaves fall off and it will be ready for the winter. It will be fine as Don Juan is half New Dawn a very hardy climber and won't die on you. Hope this helps.