Train the vines to a trellis as they grow. Tie the granadilla vines loosely to the trellis with cloth plant ties every 8 to 10 inches along their length. Follow the natural path of the vine up the trellis, allowing vines to cross over each other.
Water the soil at the base of the vines once a week so the soil remains moist without becoming soggy. Granadillas require about 1 inch of water a week, though they may need more if the soil dries quickly during the dry season.
Begin fertilizing granadillas in late winter or early spring before the vines begin putting on new growth. Supply a balanced granular fertilizer, such as a 6-6-6 blend, using the amount recommended on the package for your plant size. Apply the fertilizer every four to six weeks, never giving the vines more than 6 oz. of fertilizer at a single feeding.
Prune the granadilla vines in late winter when they aren't putting on new growth. Cut out the dead vines at the base. Trim back damaged or weak vines to the bud on the nearest healthy portion of the vine.
Harvest granadillas when the rind of the fruits becomes glossy and begins to turn yellow near the stem. Cut the fruits from the vine with a sharp knife to prevent damage to the plant.