Pruning them before they bloom removes many of their flowers. The most important thing to remember when pruning any shrub is to maintain its natural shape and beauty, he emphasizes. This is accomplished best by simply removing a few of the older canes at the base when the plant starts to get out of control. Shrubs that are only a year or two old probably do not need pruning because their canes are young and normally have not outgrown their welcome. Pruning out the older canes keeps the plant smaller and less dense, he says.
Older canes are normally the tallest and removal also keeps the plant s size under control.
This opens up the middle of the plant to the light, encouraging new growth, and keeps it looking young and natural. Blossoms will then grow throughout the plant, and not just on the top few branches. This pruning method also helps keep the plant from getting top heavy, Goodspeed says. Shrubs that are sheared or topped have a tendency to branch and thicken higher up in the shrub. This shades the lower part of the plant, reducing lower leaf and flower formation.