I have never tried them from seed !! If you can dig a small one up with any tinge of root they will grow ! They die down in winter but come up again in spring/summer ! They can take winters in the teens here as long as it warms up during the daytime !
Just read this thread and interesting. I love Passion Fruit but not a hope it would grow here although from time to time I've thought how interesting it would be if I had the space to grow various tropical plants from seed i.e. Papaya which is one of my favourites. I've never been terribly successful with avocado although I have tried many times to get a plant going from seed. Was successful with a thorny lemon years ago (gave it away)
Passion fruit is an invasive weed here although there are tame ones ! They usually will grow anywhere there is dirt !
