What are the proper pruning procedures for purple raspberries?
Proper pruning of purple raspberries promotes high yields, helps control diseases, and facilitates harvesting and other maintenance chores.
In March or early April, remove all small, weak canes, leaving only 4 or 5 of the largest, most vigorous canes per clump or plant. Cut back the lateral (side) branches to 18 inches in length.
In summer, pinch out or cut off the tips of the new shoots (canes) when they reach a height of 36 to 48 inches. Remove approximately 3 to 4 inches of the shoot tips. Since all new shoots will not reach the desired height at the same time, pinching will need to be done about once a week between late May and late July.
Finally, remove the old fruiting canes at the soil surface after the last harvest. The pruned material should be removed from the garden area and destroyed.