Mike,
Your advice about hydrating a plant well before transplanting is right on, in my experience because it is an effective way to compensate for the fact that the root system of newly transplanted rose is not fully efficient.
Margie, I am fairly certain you are growing roses in a colder zone than mine, but maybe not.
To prune or not to prune should be based upon the botany of the plant, what kind of rose you are transplanting and the weather conditions at the time of transplant in your garden.
Re: botany.... No matter how careful you may have been in keeping the root mass together to move the rose from one place to another, you will break of a lot, if not most of the feeder roots that function to transfer moisture and nutrients up to the top growth.
* The rose needs to re-grow those roots for the root system to work efficiently.
* A rose will abandon any growth that it cannot support, the top growth.
* Roses grow their roots first before they send moisture or nutrients to the top growth.
Since it is most likely, that the rose will not support the top growth well since its root system is not fully functioning, pruning the rose is just going along with what the plant will support naturally, but that depends on where you are growing your rose, the class of rose you are transplanting and more.
Re: Kind of rose you are planting ... if you are planting a rose that normally slows down at this time of year, it will abandon the top growth more quickly. For example, if your rose naturally goes deciduous during its dormant period, it is already slowing down the transfer of nutrients and moisture to the top growth.
Re: Weather conditions at the time of transplant .... There are two botanical triggers that slow down the support of top growth of all roses, deciduous or modern evergreen, which are the length of daylight available for photosynthesis and temperature. Photosynthesis in roses slows down at about 70F. When the plant slows down due to these triggers all cellular activity slows down within the plant, especially in the top growth of the rose. Studies have shown that roses will continue to grow roots at temps of -15F. Since roses grow their roots first the slow down of cellular activity does not adversely impact the growth of new feeder roots significantly unless the soil is frozen.
Modern roses never go fully dormant and store their nutrients in their canes. They will pull those nutrients down to the root system during the colder season. That is the theory behind not pruning modern roses in fall. However, they are more vulnerable to die back in colder climates and may not be able to provide the nutrients necessary to keep the rose alive during cold winters because, in a sense, they do not know how to go dormant.
OGRs, the albas, damask, many species roses, etc., on the other hand, know how to go dormant and pull all of their nutrients into the root system. Again, it depends on the botany of the plant.
I hope this helps answer your question.
Smiles,
Lyn
