Question
I have 12 bushes in RI about 30 in high[second season]. Leaving for south in late Oct.

I plan to mulch around8-10 in.

Should I prune, or not?

Thanks  

Answer
Because one never knows what winter will throw at the roses, it would be a wisdom not to prune them until the spring. I would just cut back even to the rest, any tall canes that might wave and break in the wind. Then if you get a nasty winter the roses still have more cane length left in the spring. Pruning them back now means they don't have much left if the cane freezes or dies back. Hope this helps.