Our regionally-native passionflower, Passiflora incarnata, is known to be aggressive in spreading via suckers (sprouts from wandering roots). Sometimes one or two other marginally-hardy species, like Passiflora caerulea, may survive the winter and be similarly rambunctious. Other passionflower species are too tropical (including the main one used for fruit harvesting, Passiflora edulis) and should not pose a problem as the plant won't survive the cold.

You can try a physical barrier to contain roots so they don't grow unrestrained, but we do not have data on how deep such a barrier would need to be. As an educated guess, try a minimum of six to eight inches beneath the surface. Some forms of solid plastic garden edging may be tall enough to bury to this depth (leaving a couple of inches above-ground), but otherwise you may need to research options online. (Bamboo rhizome barrier suppliers might have materials, though you won't need something nearly as extensive as that used for bamboo specifically.) If the plant will be bordered by lawn, regular mowing tends to be enough to keep suckers from persisting. There is no herbicide you can use on suckers that won't harm the desirable portion of the plant at the same time.

Miri