1. Trim off any rotten bits from your cutting. In order to sprout, you need a healthy green stem. Use a sharp knife to make a clean cut.
2. Allow the cut end to dry (callus) for at least 4 or 5 days. Lay it on a paper towel. Avoid the sun. Turn long pieces frequently so that they don't develop roots along their side edges.
3. After the end calluses, plant the cactus in a pot filled with stones or volcanic rock on the bottom, and then well drained organic cactus mix that is no more than moist. Do not water until evidence of root growth appears. You can lift the cutting and check but it usually takes several days or weeks for any roots to appear.
4. Always allow cactus soil to dry out almost completely before watering, as most are prone to rot if kept moist.
Has anyone tried this technique? Can you give us any pointers?