Spread the fertilizer evenly over the surface of the planting bed and work it in shallowly. Most of the roots of black raspberries grow in the surface layers of the soil, so blanket the ground with a thick organic mulch such as leaves or straw. Space plants three feet apart in the row, with eight feet between the rows. Right after you plant, lop all canes back to the ground, just in case they have any diseases on them. You don't have to worry about plants spreading underground like red raspberries, because most black raspberry shoots arise right at the base of the plant.
Black raspberries do spread in their own way, however.
They take root wherever the tips of arching canes reach down and touch the ground. Don't allow those tips to root unless you want to propagate new plants. Pruning Black Raspberries Raspberry canes are biennial, growing stems the first season, then fruiting and dying in the second season. So the first step in pruning is to cut the canes to the ground right after they finish fruiting. They'll soon die anyway, and removing them admits more sunshine to the new canes growing from the base of the plant.