Q. What if a rose bush is old and all the canes are thick and brownish/grey? Should I prune them way back anyways? If so, how far from the bottom? Thanks for your help.

A. I suppose that the amount of pruning you would do is dictated by how much growth is being generated by these old canes. Is the newer wood relatively healthy? Does it still produce lots of blooms? Are there no new canes being produced at the base? If the answers are yes, yes and no, then I wouldn't do much more than the 3D's, and shorten up the canes somewhat. If the bush just isn't doing anything, not much new growth, small, infrequent blooms etc. I'd be inclined to really get in there and do some serious pruning. Take out the very oldest canes entirely, cut back the others fairly hard and see what happens.