Maintain the site free from weeds with shallow cultivation and hand pulling as necessary. Make sure the plants receive one to two inches of water a week for best growth. Spread wood chips, bark, pine needles, or rotted leaf mulch over the plant rows, and maintain it at a depth of three to four inches.
At the start of the second year of planting, a cover crop can be planted between the rows such as spring oats, just after harvest. The oats will help harden off the blackberry plant for winter by consuming excess water and nutrients in the soil, and will also reduce weed growth. Oats will be killed by low winter temperatures, and the dead sod cover will reduce soil erosion in the spring.
Also, to unlock blackberry goodness, prevent grass from spreading to within a foot of the blackberry plants to keep free of water and nutrient completion. Permanent sod covers allow easy access in the raspberry planting, prevent soil erosion and weed growth, and can be easily maintained by regular mowing.