Transplant the wild blackberries in early spring or late fall for best success. Choose several healthy, thriving wild blackberry canes for transplanting and cut the canes to 2 to 3 feet long.
Find and prepare a spot in your garden for the transplants. Give each cane 5 to 7 feet of space with quick year-round drainage, good air movement and 4 to 6 hours of full sun every day. Dig 5 inches of organic compost into the top 10 inches of soil in each site, to give the blackberries rich, loamy soil.
Water the soil around the wild blackberries to make digging easier. Don long sleeves and gloves to protect yourself from these thorny plants. Dig into the soil 1 foot from your first blackberry cane and dig inward toward the cane to locate the root ball. Once you find the roots, dig around and under the root ball to lever it from the soil. Repeat with your other chosen canes. Put all the canes in a box with as much soil as possible and move them to your garden.
Plant the blackberry canes in their new sites with their roots just under the soil. Don't plant too deeply or too shallow as this leads to failure. Don't keep the blackberry roots out of soil any longer than necessary, as they'll dry.
Water each cane with 1/2 gallon of water to settle the soil and lay 2 to 3 inches of mulch over the area. The mulch keeps the soil warm and moist during establishment, and prevents drying of the roots.