Beginner Gardening: Passion vine not flowering, 1 by JulieQ

JulieQ wrote:
Last year after thinning out the privet I found numerous passiflora incarnatas on the edge of my woods. They never bloomed though.
I thought that it might help to give them something to climb so I "planted" a log upright to get them off the ground. They are climbing it like mad and look great, but still no buds or blooms. Are they late season bloomers? or can I do something else to help them produce flowers?