How to Care for Domestic Blackberry Bushes

Plant blackberries in a full-sun, well-drained garden bed, placing the bushes in a single-row hedge or in rows spaced 6 feet apart. Spread 3 to 4 inches of compost over the bed before planting and work the compost into the top 10 inches of soil to help improve drainage in heavy soils.

Water the blackberries once a week from June until until the last berry is harvested. Provide 1 inch of water at each irrigation unless rainfall for the week equals 1 inch or more. Properly watered soil feels moist to at least a 6-inch depth.

Pull any weeds as soon as they are noticed, but avoid cultivating the soil to prevent weeds as blackberries produce shallow, easily damaged roots. Spread a 3-inch layer of mulch under and between the plants to prevent weed growth and also to help retain soil moisture.

Fertilize blackberries in June each year. Spread 5 lbs. of 10-20-20 analysis fertilizer along each 100-foot row. Avoid placing fertilizer on the foliage or canes, as it can cause burning. Fertilize a second time once the bushes begin blooming, applying 1 lb. of ammonium nitrate fertilizer to each 100-foot blackberry row.

Prune new canes in early summer with a pair of pruning loppers. Cut off the top 2 inches of each newly grown cane to encourage branching and full growth.

Trim out the canes that just finished producing berries in fall once the harvest is complete. Cut the canes off at the base with shears. Canes only fruit once and must be removed to encourage the growth of new fruiting canes.

Harvest blackberries when they are full and firm by twisting them slightly and breaking them from the stem. Harvest one to two times a week as the berries ripen.