How to Care for Thornless Blackberries

Grow thornless blackberry bushes in sites where they get full sun, good drainage, and plenty of space. Blackberries will grow in partial shade, but they bloom and fruit better in sun. The bushes suffer when they're crowded or exposed to standing water.

Water thornless blackberry bushes frequently, with 2 to 3 inches of water every week during the dry season, and 1 inch of water a week during winter. Do not allow your blackberry bushes to go dry, especially when they're blooming and bearing fruit.

Keep a 3- to 4-inch layer of mulch on the thornless blackberry patch at all times. Mulch helps keep the soil moist and warm, and discourages both weeds and pests. Blackberry bushes do not do well with competition from weeds and grasses.

Add organic compost to the soil every spring to increase drainage and long-term nutrition in the soil. Mix 2 inches of compost into the top 2 inches of soil around the plant. Give the thornless blackberry bushes actual nitrogen in spring as well, per manufacturer directions. Always add fertilizer and compost just as spring begins.

Trellis trailing blackberries, which require support. Put a trellis or arbor near the plant for training, and use soft cords to tie the main canes of the bush to the trellis.

Prune thornless blackberry bushes every winter according to their variety. Erect blackberry bushes require different pruning than trailing blackberries, while various training systems dictate different pruning methods.