Most roses need some pruning every year. The best time to do the pruning in the Washington area is late March or early April, just before new growth starts.
Hybrids teas and grandifloras are pruned about the same way, floribundas require little pruning other than removal of dead and weak wood, and large flowered climbers should have winter-killed stems removed. After you have had the climbers three or four years, the oldest canes should be removed every year at the ground level and new ones allowed to take their place.
The type of pruning done on hybrid teas depends on what you want from them. Prune heavily if you want large, specimen blooms for exhibition, lightly if you want early blooms and lots of them throughout the summer.
The more leaves the plant has, the more food it can produce (photosynthesis) and the more flowers there will be. It takes about 15 healthy leaves (not leaflets) to produce the food for one bloom.
The first step is to remove all dead and diseased wood. Cut about an inch or two below the black part of the stem. If there are no buds left, remove the entire stem. The least desirable of two branches that rub against each other should be removed. They scratch each other with their thorns, permitting infection by disease organisms. All small twigs on the upper part of the plant should be cut off.
Cut the main stems back to one, two, three or four feet, depending on what kind of flowering you prefer.
Some specialists say roses that suffered badly from the blackspot disease last year should be cut back to 6 to 12 inches. They say the fungus overwinters on the canes and removal of most of the canes may reduce the chances of new infections this year. The prunings, of course, should be removed from the garden area.
Other specialists believe heavy pruning helps very little in blackspot control and proper application of a good fungicide immediately after the disease appears will take care of it.
In many gardens roses are planted only about three feet apart and some pruning may be necessary to keep them from crowding each other.
Use sharp tools to prune the roses. Dull shears are likely to crush the stems and the wounds heal slowly if at all.
When a cane or branch is shortened, the cut should be made one-eight of an inch beyond a bud or stem. If made at a greater distance, a stub will be left and the stub will die back and infection can occur.
Miniature roses should have long shoots shortened. Thin out the top and cut it back somewhat.