How to Grow Blackberries in Delaware

Select a blackberry planting location that receives full sunlight for a minimum of six to eight hours each day and has a slightly acidic soil. Test the soil pH to verify it has a value of 5.0 to 7.0.

Amend the planting area by tilling in 2 to 3 inches of organic compost. Add ground rock sulfur to lower the soil pH or limestone to raise the pH, if needed. Follow the package application rate for the current pH level.

Create planting rows 4 feet apart to allow access and air circulation between the rows. Plant container-grown blackberries in a hole that is twice as wide and the same depth as the root ball. Space the plants 18 inches apart.

Water the blackberry canes immediately after planting to moisten the soil to approximately 6 inches deep. Provide supplemental water during the growing and fruit-production seasons when the weekly rainfall in Delaware is less than 1 inch. Avoid letting the soil dry completely to prevent stress on the plants.

Place a 4-inch layer of organic mulch along each planting row and around the canes. This helps with soil moisture retention and limits weed growth that competes with moisture. Clean straw mulch works well for blackberries in Delaware.

Apply a 10-20-10 fertilizer to the soil around the blackberry canes at a rate of 5 lbs. for each 100 feet of row. Apply fertilizer when the blooms appear and again after harvest.

Prune the blackberries each spring to remove dead or damaged canes. Prune 3 inches from the end of new canes in June to stimulate the growth of lateral branches. Prune to remove 2-year-old canes in the fall season after harvest.