I only have a method for growing them from seed. Plant seed, waste your time attempting to grow them, use compost in a raised bed elsewhere in the garden, go plant some tomatoes there... you now have maypops 😁
Discussion
That’s no joke, they’ve popped up all over. I’ve heard seed starting is tough but thinking a root cutting would be pretty successful given their aggressive nature.
Yeah the hardier one Passiflora caerulea gets everywhere here even after I have taken it out! With those root cuttings use some EM on it. If you don't have that just components of it e.g yeast or lactic acid bacteria from yogurt etc should help them form roots faster. I used some bokashi with biochar on some rose cuttings last year and they all took for once.