Pruning a rose bush can be a daunting task, especially if the rose bush is large and climbing. Aside from the issue of thorns, the questions of when, where and how to cut back a climbing rose bush should be answered before you begin. Pruning correctly will assure prolific bloom and a longer life for your rose bush. Don't be shy about cutting your rose back. It will be healthier and happier for it.
Prune a climbing rose bush in late winter or early spring before it has broken its dormant period.
Remove any foliage that is hanging on, as old leaves can harbour dormant fungal spores. This also allows you to get a good look at what you're working on.
According to Fine Gardening.com, you should work first on removing any branches that are spindly, diseased or injured. Cut these flush with the cane from which they grew. If you find any old, woody canes that did not bloom well last season, remove those as well, along with canes that have become too long and have outgrown their support. Trim overgrown canes back so that they are more easily supported. Finally, if you find any canes on your rose bush that are crossing or growing in an awkward manner, cut those back.
Take a look at your work so far. Make sure you've removed all sick, injured and awkward canes. Then choose the canes that will become the framework for the next season's growth. When you are pruning a climbing rose, search out canes at varying heights that are filled with swelling buds and side shoots, which are called laterals. These will be the framework for your climbing rose. If you find canes that don't look like they will be producing much growth, prune them out.
Inspect the canes you've chosen to keep. According to the University of California, Davis, Tulare County Cooperative Extension, you should unfasten each cane one by one and prune back the cane's lateral shoots, so that each is down to two or three buds. Reposition and fasten the canes on the support. Make your cuts about one quarter of an inch above each bud.
Rake up and dispose of all pruned canes and branches, and fallen or removed leaves. Spray your rose with dormant oil to eliminate any pests.