Prune roses to improve their appearance to remove dead wood, and to control the quantity and quality of flowers produced. If roses are not pruned, they soon grow into a bramble patch and the flowers are small and of poor quality. Remove spent blooms to encourage new growth and recurrent blooming.
Use sharp tools to prune roses - a fine-toothed saw for cutting large, dead canes, and pruning shears and loppers for all other pruning. Hook and blade pruners give a cleaner cut than anvil-type pruners. Cut back to sound wood just above a bud at a 45 to 60 degree angle. Do not use anvil-type pruners because they crush the stems.
Pruning Bush Roses: Prune bush roses in early spring just before growth begins, usually in mid- to late April in the North Central region. First, remove all dead wood; live wood is green and has live buds that are beginning to swell. Cut 1 inch or so below dark-colored areas at a 45 to 60 degree angle, about 1/4 inch above an outward-facing bud. If no live buds are left, remove the entire branch or cane. The pith (center of stem) should be white. Remove stems with tan centers because they will eventually die back.
Next, cut out all weak growth and any canes or branches growing toward the center of the bush. If two branches cross, remove the weakest one so that the center is open to light, air circulation and growth.
Finally, shape the plant by cutting the strong canes to a uniform height. Healthy, vigorous hybrid tea plants may be pruned to a height of 12 to 18 inches. Prune less vigorous varieties less severely, about 16 to 24 inches tall. Also, floribundas generally do not need to be pruned as severely as hybrid teas, but prune them in a similar manner.
In the northern parts of the North Central region winters are so severe that much of the top of the plant is killed. Under these conditions, don't attempt to shape the plants; just cut out the dead wood and save as much live wood as possible.
In fall, prune hybrid tea and grandiflora bushes to a height of 24 to 30 inches if they are located where winter winds will whip them.
Pruning Tree Roses: In the northern parts of the North Central region, tree roses do not require heavy pruning in the spring, but will need some pruning during the growing season to keep the tops from becoming too large for the stems.
After removing dead and spindly wood, cut back live canes to lengths of 8 to 12 inches and shape the overall structure of the plant.
Pruning Shrub Roses: Prune most shrub roses after they have bloomed. As a rule, these plants are very hardy, so pruning is usually necessary to thin and remove old canes. Shrub roses do not require shaping; in almost all situations, shrub roses are most attractive when they are allowed to develop a natural shape. Pruning Climbing Roses: Prune hardy ramblers just after they have bloomed. Pruning stimulates new cane growth and development of laterals on which the next year's flowers will grow.
Where ramblers are trained to a trellis or support that is so high that one season's growth will not cover it, cut off some of the older shoots. Shorten strong, vigorous canes that are lead pencil-size to fit the trellis or support. This pruning will stimulate lateral development that will eventually cover the trellis.
In spring, remove all dead canes and weak branches. Prune sparingly-removing too much wood at this time will reduce flower production. Many of the large-flowered climbers, especially the everblooming types, do not grow as much each year as the hardier climbers, so less pruning is necessary. This rule also applies to slow-growing cultivars.
Roses are propagated by bud-grafting a particular cultivar onto a rootstock of a more vigorous grower, such as a multiflora rose. Suckers often arise from the rootstock, and because they are more vigorous than the bud-grafted cultivar, they will eventually crowd out the desired flowering cultivar. Sucker also have different foliage and flowers, which will help you identify them. Remove suckers by pulling them out or cutting them from the rootstock below the soil line whenever they occur. If the bud union is not visible, carefully scrape back the soil around the stem to make sucker identification and removal easier.