When we planted our passiofruit it had a volunteer seedling in the pot. Of course I left it there and planted them both on the transpiration pit for the biogas system. They both grew strongly and eventually one started flowering. The flower looked like a passiofruit flower to me, so I eagerly awaited some fruit forming; this never happened, the flowers just withered and fell off.
After a lot of googling and reading in my library, I discovered the blue passionflower; a weed in Australia. My flowers look just like the photos, and I was disappointed.
The flowers are beautiful, but the vine is very invasive and the leaves and unripe fruit are poisonous. So the vine has to go. We cut the stem at the ground and pulled down as much of it as we could. The vine was stuffed into garbage bags and left in the sun to die. I plan to empty the lot into the mulch pit eventually, but I want to be sure it’s dead first.
It looks like we have a few years of pulling up seedlings in front of us as it is a very invasive weed. On the positive side, the actual passionfruit vine is getting buds on it now.