Feeding

• Water blackberry bushes regularly. Master gardener Walter Reeves recommends fertilizing with 10-10-10 in spring and after harvesting the berries. Use 1/4 pound per plant for the first two years. After two years, use 4 pounds in the spring and 1/2 pound after harvesting.
  
  

Diseases

• Blackberries are subject to several diseases that are preventable with proper mulching, which also helps with moisture, pest and weed control. Choose healthy blackberry bushes when planting. The University of Georgia Cooperative Extension Service recommends removing nearby wild blackberries to prevent possible viral disease. Harvest ripe berries promptly.
  
  

Pruning

• In early spring, remove all but the largest canes, leaving between eight and 16 canes on trailing blackberry bushes and tie them to the trellis. For upright bushes, remove all but four or five canes. As the season progresses, cut any lateral canes to no more than 15 inches long. For both varieties, remove all fruit-bearing canes after the harvest, leaving the younger canes to mature for the following season.