While climbing roses may be trained to climb over stone walls or up trellises or fences, if they are not trimmed back at the end of each growing season, they will become unmanageable tangles of briars that bear very few blooms. To keep climbing roses robust and full-blooming, the canes must be properly trimmed back in mid- to late-winter, when they are totally dormant. While anyone can trim a plant, success lies in knowing how to trim a climbing rose properly, and climbers do not need to be trimmed as severely as other types of roses.
Use sharp scissors to remove the leaves from the canes. Fungal spores reside on the leaves, so to protect the plant from damage in the spring, you have to get rid of the leaves.
Locate any branches that appear to be injured, dead or diseased, and cut them off at an angle right at the cane (main trunk). Find any wild or overgrown branches and cut them off at the cane, too. If you notice any branches that are overlying others, making a web of branches, cut them off at the cane as well.
Stand back from the plant and take a good look at it. Look for the four to six healthiest main canes that have side buds or horizontal branches growing from them. These "keepers" are usually the young green ones. Any other main branches that are not healthy-looking or do not have side branches with buds can be cut off.
Untie any main canes that may have been tied to the trellis last season. Re-tie the best main canes to the trellis using material that stretches (such as strips of pantyhose) to allow for growth, and shorten the side or lateral branches so they have only two to five buds on them by cutting the branch .25 inch above the last bud. The more horizontal branches you have, the more flowers you will have.
Tie the trimmed horizontal branches to the trellis using a strip of pantyhose. Stand back and look at the whole plant again, keeping in mind that the main goal is to have the climbing rose spread over the trellis, but not overcome it.