I have 2 bushes about 4' tall with canes about 1 to 2" in diameter. There are very few branches(?) of these canes. When can I cut them back and how far?
Pruning Rose Bushes
Please check out this article on pruning roses that I am providing a link to. Pruning the larger canes can be problematic as some will simply die if pruned more that 6 or 8 inches. Do not prune back below existing foliage level unless the canes die back substantially over winter. Article Link> https://www.gardeningknowhow.com/ornamental/flowers/roses/pruning-roses.htm