Cut the entire blackberry bramble back to 6 inch stems.
Use the hoe to cut into the soil in a 3-foot radius around the blackberry. Pry the roots from the soil.
Place the roots immediately into a bucket of water to soak while you prepare the new planting hole.
Dig up a 1-foot square area in the new planting area. Combine equal parts of compost and sphagnum peat moss in a wheelbarrow and then add it to the soil removed from the planting area. Mix well and place the amended soil back in the planting area.
Dig a hole the same depth as the blackberry has been growing in, and three times the width of the rootball. Place the roots into the hole and backfill with soil. Lightly press the soil around the base of the plant with your hands. Water the area deep enough so that the rootball is saturated.
Fertilize the blackberry with 5-10-5 as soon as new growth appears.