Outdoors, most passion flowers are hardy in Zones 9 and 10. Hardy to Zone 5 with protection, wild passion flower loses its leaves in colder regions but is evergreen farther south. Plant passion flowers in full sun near a support. They will grow best in a deep, moist, well-drained sandy loam that has been enriched with compost or leaf mold. Prune the vines heavily in fall or early spring to remove deadwood and to control rampant growth. Propagate additional plants from cuttings 4 to 6 inches long, taken at any time during active growth. Germination of seed is slow and uncertain. If your plant is growing in full sun in deep, well-drained, moist soil with its roots mulched and it still doesn’t bloom, I would probably remove it and put in something else. As house plants, passion flowers grow best with four hours or more of direct sunlight a day and night temperatures of 55 to 65 degrees F and day temperatures of 68 degrees F or higher. Plant in commercial potting soil and provide a climbing support. Keep the soil evenly moist. Feed the vine every two weeks with an all-purpose fertilizer applied at half the strength recommended on the label. When growth slows in the fall, stop fertilizing and let the soil dry slightly between waterings until new growth starts. In January cut the plants back to 6 inches to force new growth.

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