Trailing blackberries should be summer tipped at about 6 inches above the highest trellis wire and tied to it during the summer months. For dormant pruning, select five to eight of the strongest canes, remove all laterals originating on the lower 3 feet of the canes, and tip back remaining laterals to 12-18 inches. The home garden environment provides some unique opportunities for trellising. Trellis systems generally do not affect the type of pruning a plant receives. In other words, black and purple raspberries still require summer tipping, but the trellis determines the height of tipping.
Trellises allow plants to support more surface area for fruit production.
Several trellises have been experimented with successfully. See Figure 7.3 for possible trellis designs.