I've never quite had the foresight to root prune any of the roses I have moved. I'm rearranging roses now. I dug out four last week, three of them retained really nice root balls and I don't expect them to even wilt. The fourth (Carefree Beauty) lost all of its soil when I dug it, so I cut it back severely and treated it like a bare root.

Which rose are you moving, and how long has it been in its present spot?

Connie

Do it in spring before you transplant/plant. It would be almost impossible to do it now unless you dug them up, and that would not be a very cool idea with winter coming on.

I want to move my Jacob's Robe, which has been in its present spot for a year and a half.

Before you chop the roots, do you know if your soils have the bacteria that makes root galls/crown galls? If so, you may want to wait until after you dig the rose up, rinse the roots thorougly, and then cut them back. Or you may find that the roots aren't all that large and don't need to be cut back at all.

Once again, I diagree with Roseman. Virginia has wet winters most years and the rose would be better off transplanted in fall (and letting rain help the roots get acclimated), rather than waiting for spring when heat and drought can happen all too soon.
BTW, frost isn't enough to make the rose go dormant. Often roses will hold onto their leaves while temps go into the twenties and teens. They will slow down, and some winters that's all we can expect them to do.

I had originally planned to move it this fall, but when I read about root pruning I thought best to wait. But I'll happily move it sooner rather than later.

Even covered in 6+ feet of snow drifts last winter my roses never really defoliated. So should I wait until November (or later) when the rose seems to have stopped putting out new growth? Or do it now, so it can acclimatize before it gets cold?

Thanks for all this valuable advice!

If it were my rose, I would go ahead and move it now. That's what I'm doing ... moving roses and planting new roses. The roses like the cooler fall weather, and so does the gardener. :)

Connie

I'm with anntn6b--I try to avoid any damage at all to the roots due to fear of crown or root gall. One they get that, the rose goes to heck.

Is gall as much a problem in colder climates as it is here in CA? I will dig a monster hole to avoid slicing into the roots. I always thought though that in colder climates root/crown gall was not so much of a problem as here where the soil never really gets that cold.

I have never intentionally root pruned. And, if the rose is only 1.5 years, there aren't a lot of roots to prune. I would imagine that technique used for mature (10+ years) roses, but not for relatively new plantings.

I wouldn't root prune a rose moving it from one hole to another on my own place; the more roots that survive the better. Commercial bare-roots (particularly grafted ones) are root-pruned primarily for packing purposes. I'm always happiest buying bare root roses if they're own-root and come with the nice fibrous root mass still on.

Here is a link that might be useful: Garden Musings blog.