Successful pruning can be accomplished in either late fall or early spring. If pruning in late fall, wait until the leaves turn color and start to fall. The longer you wait, the more food will be delivered to the root system and the more vigorous your rose will be in the spring.
Pruning too early in the fall can initiate soft late growth that may not withstand hard frost and will winterkill. Most growers still prefer early spring for their pruning. Many of the roses we grow in the north will kill back a certain percentage each winter. If you wait till spring to prune, it will be easier to assess the amount of damage that the plant has suffered, and the plant can be pruned accordingly. The dead portions can be removed and the remainder shaped. However, spring can often be a very busy time for gardeners. If you know that time will be at a premium in the spring, by all means prune in the fall. The hardier varieties will probably not suffer. Just leave the more tender types till spring.
Pruning can range from removing unwanted buds to severely excising canes. Proper pruning stimulates growth at the buds closest to the cut, which produces new flowering stems.
The first step in pruning any type of rose is to remove any dead, damaged, diseased, or weak and thin canes, cutting them off flush with the bud union or, in the case of own-root plants, flush with the crown. Look for any canes that are broken or wounded, or that have cankers (dark, sunken lesions caused by a fungus), and prune below the injury, at the highest point where the pith (the central portion of the cane) is healthy and white. Make the cut exactly 1\4 inch above a growth bud. If the injury extends below that point, cut to a lower growth bud.
Next, remove canes that are growing into the center of the plant or those that cross each other. Canes that grow inward keep light and air from the center of the plant and will eventually cross, chafing one another. These abrasions can become entry points for insects and diseases. Using shears, cut these canes down to their origin, whether that is another cane, the bud union, or the crown. It is important to keep the center of the plant open to let in sunshine and allow air to circulate freely.
Always prune to an outward-facing bud so that canes do not grow into the center of the plant. Prune close enough to the bud that no stub remains to die off and harbor insects or diseases but far enough away that the bud will not die. A good distance is about 1/4 inch above the growth bud. Equally important, cut at the proper angle so that water runoff won't drip on the bud or collect in the cut and retard healing. The ideal angle is 45 degrees, slanted parallel to the direction of bud growth.
Further maintenance
A few pruning techniques can be used with good effect during the growing season. When a cluster of flowers has finished blooming, that section of the stem does not grow any more. New growth starts from the first vegetative bud below the flower cluster. If the old cluster is pruned off, it will stimulate this bud into active growth and within a few weeks, you can have more bloom. This is effective only on repeating roses. Removing the old blooms will also eliminate the possibility of seeds forming. The plant spends a good deal of energy on seed formation, and when these old blooms are pruned off, the plant has more energy to form new growth. Obviously, if you want rose hips you won't want to practice this technique.
Some roses leave their petals in a messy, brown lump when they have finished blooming. The removal of these spent blooms, or "deadheading", will help to maintain a fresh look to the plant and will encourage rapid new growth.
Be on the lookout for problems such as rose galls. These swellings are formed by small insects that lay their eggs in the stems. Upon hatching, the larvae feed on the inside of the stem, causing it to swell. If allowed to complete their life cycle they will infect other roses. Cut out any unnatural swellings as soon as they are noticed. Various infections such as cankers should be cut out as soon as you notice them. These often start on dead wood such as pruning stubs or winter-injured branches. They can quickly work their way into live tissue and cause a great deal of damage if not tended.
