Blackberries are easy to grow. In fact, they can become invasive if not properly pruned and trained. Blackberries come in two varieties - upright and trailing. Trellising is beneficial for the varieties with trailing canes. They produce fruit on second year canes. In the fall of the 2nd year, prune the canes that have produced during the summer to ground level and thin others to approximately 4 canes per foot of row. Cut off suckers which grow outside of rows. Trim remaining blackberry canes to 7 feet.
Water blackberries once or twice a week during dry periods. Feed new plantings every 8-10 weeks with three ounces of 8-8-8 fertilizer from early spring until fall.
Mature vines should be fertilized using five ounces per plant once in early spring and two more times during the summer months.