If your passion flower vine (Passiflora spp.) was irresistibly beautiful when you found it in the garden center, you are probably disappointed and frustrated if you can’t convince the vine to create more intricate blooms now that it's home. This fast-growing plant is usually a prolific bloomer and generally does well outdoors in U.S. Department of Agriculture plant hardiness zones 5 through 9. The plant can be grown indoors in colder climates. Fortunately, if your plant is growing in the proper climate conditions and you have fed it, watered it and loved it to no avail, you can try a few simple things to coax it into blooming again.
Verify that the plant is in direct sunlight. Even if it was when you planted it, a growing tree canopy or newly installed fence may now be shading the plant. Remove any shade-creating obstacles or move the plant to a sunnier location.
Water the passion flower as needed to ensure that it receives 1 to 1.5 inches of water a week. (Reference 5) Vines planted outside may not need watered if rain provides adequate irrigation.
Fertilize the passion flower vine less often or stop fertilizing altogether. Too much nitrogen causes the plant to produce lots of new leaf growth at the expense of flowering. When you do fertilize the vine, use a fertilizer that contains less nitrogen than it does phosphorous.
Pinch back or prune off spent flowers before they go to seed to encourage more blossoms.