Passion flowers are semi-hardy perennials that grow on vines. They are native to the southeastern United States, and are reliably hardy through USDA zone 5 with winter protection. They die down to their roots in fall and re-emerge in the spring. Passion flowers bloom in summer with sweetly scented white and purple blossoms. They produce egg-sized berries in late fall that make an excellent jam.
Pick a planting site for passion flowers that is in full sun with sandy, well-drained soil. Do not plant where water collects after rainfall.
Improve the soil. Lay down a 3-inch layer of compost at the planting site. Dig it into the soil with a spade and rake the area smooth.
Dig a small hole with your garden trowel and insert the roots of the passion flower transplant into the hole. Back fill with compost, then firm it around the roots gently with your hands.
Water in individual transplants with a watering can. Thereafter, provide at least the equivalent of 1 inch of rainfall per week; passion flowers need soil that is evenly moist to produce the most flowers.
Apply an all-purpose, granulated fertilizer to the ground in a circle around the transplants, following the manufacturer's recommended application rates. Put down a second application of fertilizer six to eight weeks later. Thereafter, fertilize once in early spring when new growth appears, and again six to eight weeks later.
Mulch the soil in the growing bed with 4 to 6 inches of organic mulch. Use hay, straw or shredded bark to help keep the soil evenly moist and discourage the growth of competing weeds.
Cut the faded foliage off in late autumn and protect the roots by applying a 1-to-2 foot layer of fallen autumn leaves. Remove the mulch in mid spring when new growth is evident.