New canes originate from the underground crown each season on vigorous plants. The younger canes are more productive, so it is desirable to remove the older, weaker canes by cutting them out at the soil line. This leaves a preponderance of the younger, more vigorous canes and encourages a continuous replacement of new canes. Young plants, therefore, require little pruning for the first three or four years.
Branched canes are also more able to support the crop off the ground than unbranched canes.
After the crop is harvested, the old fruiting canes should be removed at the soil line. Pruning red raspberries Red raspberries should be allowed to produce long, unbranched canes rather than branched canes like the black and purple varieties. The new canes are, therefore, unpruned during their first season's growth. At the start of the second season, they are topped to a height that will permit them to support themselves and keep the fruit off the ground. If the plants are supported by stakes or a wire trellis, they can be pruned to permit more fruiting wood.