Dig two holes, each 1 foot deep, one on either side of the raspberry plant or row of raspberry plants. Insert 6-foot posts into each hole, then firm the soil around the posts to keep them in place.
Tie the end of a string of rust-proof wire around one post at a height of 2 1/2 feet. String the wire across to the other pole and tie it to the pole. Tie another piece of wire at 5 feet. Secure the tied wires to the poles by stapling them in place with a staple gun.
Allow the canes of the raspberry bushes to grow until they are long enough to reach the first wire. Gently raise the canes up to the wire. Wrap green garden tape around the canes, where they meet the wire, to hold them in place.
Tie the canes to the 5-foot wire with the green garden tape by loosely wrapping them in the same fashion, if they get that high during the growing season.
Cut back any dead, spindly or weak canes all the way to the ground at the end of the growing season. Unwrap the tape securing these canes to the wires and discard them.