Passion flowers include more than 450 species in the genus Passiflora. Some species produce prolific, delicious fruit when grown in a tropical or subtropical climate. Their flowers are showy and unusual; in 1620, a Jesuit priest named them because they reminded him of the passion, or crucifixion, of Jesus Christ.
If you live in USDA hardiness zone 5 through 9, you can grow passion flowers all summer long, along with the bees and butterflies, whose larvae feed on certain species of passion flower.
Purchase seeds of a variety that does well in your hardiness zone. Native passion flowers occur in many areas, and these will be the best-adapted species for your climate and growing conditions. You also can start new plants from cuttings of an existing plant, but these can take three months or more to form roots.
Soak seeds in warm water for 12 hours or longer before planting. Germination rates can be low and can take up to one year. Consider buying a plant if you want to speed the process and get your passion flower growing as quickly as possible.
Select a sunny, protected spot in your garden against a building where the plants will have support for their rampant vines. Passion flowers need moist, but well drained soil. Add a shovelful of compost to your planting hole.
Place your young passion flower plant into the planting hole after your area's final frost date, and then fill with the soil you dug out earlier. Firm soil down around the plant and water thoroughly. Keep the soil moist for the summer growing season.
Fertilize with compost, worm castings or a 10-5-20 fertilizer about four weeks after you plant your passion flower vine.
Mulch with leaf litter, peat moss or compost to keep the soil cool and moist and to protect the root system from cold temperatures.
Prune old growth in fall. Pruning will encourage new growth the following spring.