Cut about 5 inches from the top of a Hylocerus joint at an angle. Let the cutting dry completely over two weeks. There should be a thick callus on the cut part of the cactus piece before you plant it.
Fill a pot with sandy, well-drained potting soil. Use your fingers to make a hole about 1-inch deep and just wide enough to slip the cutting into. Press the soil gently around the base of the cutting.
Set your cutting in a very warm area with bright, indirect sunlight. Wait until the cutting roots before watering it. The roots will begin to show through the soil. Water the soil until it's damp but not soaked.
Place river stones in a flood tray and fill the tray to the top of the stones with water. Set the potted cutting on the tray. This creates a humid atmosphere around the plant. You should also mist the cactus about every other day. Hylocerus loves warm, humid, tropical conditions.
Water your hylocerus when the soil becomes bone dry. It tolerates overwatering better than most cacti, but still hates soggy conditions. The hylocerus will flower and bloom at night. The flowers will wilt quickly and turn into dragon fruit. Harvest when the fruits are firmly pliable and bright pink.