Maypop can set some fruit alone, but it does better with a partner. Maypop can set some fruit alone, but a separate compatible vine usually improves fruit set more reliably than another runner from the same patch. It flowers in mid-late bloom, so a partner has to be flowering at the same time to be any use. Usually grown in USDA zones 5-9.
No single variety stands out as the obvious partner, but that is not a problem here: Second maypop vine all bloom close enough to work. Pick whichever your nursery actually carries. Keep compatible vines on the same trellis or nearby supports so pollinators can move between fresh flowers the same day.
One thing to keep in mind. Passion fruit partners work best within the same species group. Maypop is best matched with another maypop or other compatible Passiflora incarnata planting, not just any passion vine. Maypop often fruits better when pollen comes from a separate compatible vine rather than another runner from the same patch.
To put that into practice: at a minimum, one self-fertile passion fruit can fruit alone, but two compatible vines are the safer plan for unknown vines and for maypop. Better still, grow two compatible vines with overlapping bloom. For maypop, use a separate plant, seedling, or source rather than relying on one spreading patch. If flowers open well but fruit set stays poor, add another compatible vine or hand-pollinate before assuming the site is the problem.
