I know I shouldn't, but every year I let them grow.  I don't let them ALL stay, because the vines can take over the tomato cages, the pathways, the fence, the yard, and yes, the world!!!  But I love these flowers so much, I let some stay.  

 

As you can see, the leaves are kinda chewed up, but that's ok:  I'm not looking at the leaves.  I only see the flowers.  Maybe that's why it's called Passionflower:  we love the flowers with a passion.

 

 

HAPPY GARDENING !!!