Take a cutting from a healthy, mature hylocereus. Use pruning shears to make a slanted cut at the base of a stem that measures 6 to 15 inches long.
Apply a fungicide to the cutting and leave it to dry and heal for seven to eight days in a dry, shady area.
Fill a pot with a commercial potting mix designed for growing cacti. Insert the cutting into the potting mix so half of it is buried.
Place the pot in a bright area, ideally a location that gets plenty of direct sunlight.
Water the plant whenever the soil begins to dry. Dump out any water that accumulates in the saucer or drip tray beneath the pot.
Install a sturdy trellis in the pot if your hylocereus begins to get too floppy. Train the branches over the trellis to help support the heavy flowers and fruit that may develop.
Fertilize the hylocereus with a water-soluble balanced fertilizer on a monthly basis during the growing season of spring and summer.