Well the best time to move an established rose is in the very early sspring while the plant is still dormant. Dig as large of a root ball as you can in order to minimize shock t o the plant.I recommend using a sharp spade, working around the plant. I can't see your specimen, but I'd start digging about two feet or so from the crown of the plant. If the plant is dormant it won't hurt it if you break some roots during transplanting. And, of course, remember to move it to a sunny spot. "