Early spring is for major pruning. Prune too early and a late-freeze could kill the tender new growth your pruning encouraged. I try to listen to my roses: when they begin to bud and leaf out, I prune.
Summer is for deadheading. Pruning off finished flowers will help your rose bloom more and for a longer period.
Autumn is for trimming back extra long canes that could be damaged by winter wind. Cleaning your tools is especially important now when rose diseases may be present at the end of the growing season.
Clean, sharp snips and pruning tools. I rub the blades down with alcohol on cotton balls or a rag.
Cut on an angle just above a bud. Cut too far above a bud and the stub of wood will shrivel and could spread decay further in that cane. Cut too close and you could damage the bud.
Remember the 3 Ds: Dead, Diseased, Damaged. Begin there by cutting dead wood back to the ground. If the canes are green inside, they are still alive. You can cut damaged and diseased wood all the way back or just well beneath the affected portion.
For shrub roses, I reduce the bush by about a third. Cut back to just above a healthy looking bud break.
Other things to look for: you might prune out thin, wispy growth. You might prune out growth that crosses. When canes rub together they can cause wounds that may weaken or kill the wood.
Finally, clean up. Cart away the pruned leaves and wood in order to discourage pests and disease.
A few additional tips:
- Climbing roses: much of the above still applies, but you will want to learn more about the difference between main canes and lateral canes; climbing roses flower along their lateral growth
- One-time blooming roses: These should be pruned only after they bloom. Otherwise, you might not have any flowers that year.
- Hips: Many rose varieties will set beautiful (and nutritious!) rose hips. These are the fruit of a rose. Toward the end of the growing season stop deadheading in order to let the hips develop. They are beautiful, good food for people and wildlife, and they signal the rose that it’s time for dormancy.
- It’s very unlikely that you will kill a rose by overpruning or pruning badly. At worst, you might sacrifice of a few of that season’s blooms.