Purple Passionflower / Maypop

This passionflower (Passiflora incarnata) is native to the southeastern United States and with warming winters has been creeping up to overwinter successfully in the mid-Atlantic and even the northeast. Some sources cite it as being  “woody” in hotter climates, but I have never encountered evidence of it being anything other than a senescent vine no matter where it’s grown. This means it is a perennial vine that dies back every winter and grows back up from the ground in the early summer.

Like many of the North American natives, it’s a bit of a challenge to start from seed. Some suggest using cold stratification to mirror the plant’s natural life cycle. Others have had luck soaking the seeds for 24 hours in warm water prior to planting. To help break through the tough seed coat, the seeds may also be scarified (lightly nicked to facilitate the entry of water into the seed) with a light sandpaper or small blade. Be patient - germination can be prolonged (3 to 6 weeks) and sporadic; not all seeds will come up at once.

Because this vine is a perennial, you may have best luck starting it in the spring, potting it up into a larger container over the summer,  letting the roots develop for several months, and then planting it out into the garden in the fall. It will require some attention and care as it gets established over the first year or two. 

After that your only concern will be reigning in its joyfully uncontrollable growth. So be mindful where you plant it! Once established, it will spread prolifically underground, and the 30ft vines will reach far and wide in every direction. For this reason, it’s best to plant it where you can give it lots of space and where you’re happy to have a wilder looking and feeling zone. 

It will beautifully climb and cover any fence or trellis that it can cling to with its tendrils, but it will also spread over ground and create a lush ground cover. Regardless of growth habit, it is difficult to describe the effect of its ostentatious purple and white blooms popping off all summer long (June-September here). In a corner of my South Jersey yard this vine has interplanted itself with pokeweed (Phytolacca americana) and cup plant (Silphium perfoliatum) and this is easily the most lively part of the garden - profusely buzzing with bumblebees busily zipping from flower to flower and dodging butterflies and moths at every corner. Here it is definitely host to the variegated fritillary caterpillar, to the south and west of here it also reportedly hosts the gulf fritillary.

It appears to be a profoundly useful plant to our insect neighbors, and can also be very useful to us! You’ll likely get fruit production happening by the third year. Although it seems that there is a lot of reported variability in flavor, the PGS seed stock came from particularly delicious fruit that in my opinion compare well to the tropical ones that cost $8 a pop at the supermarket. Fruit is fully ripe and at maximum sweetness when its bright green color starts yellowing and it falls off the vine. Just tear it open and slurp up the fruit - you can chew up and eat the crunchy seeds or suck off the jelly fruit and spit them out. Here the fruit starts ripening in September and continues through mid-October. Harvested earlier than that it’ll be more sour, which can also be nice. 

The leaf and tendrils are a popular nervine - a calming and sleep-supporting herb often found as a key ingredient in grocery store sleepy tea blends. It’s not a particularly delicious flavor on its own - kind of grassy and nutty and strange - but I do find that a strong cup of the dried herb steeped for 15 minutes or so can really help calm down the system and move it closer to sleep. It’s also indicated for spasmodic pain and can provide some relief for things like menstrual cramping.

The leaf also has cited historical use as a “pot herb” - a leafy plant cooked with oil or water as a green, sometimes with other types of greens. I enjoy snacking on the crispy vine tips in the garden, and sauteeing the shoots and tops of the vines in olive oil with some garlic. Older larger leaves are OK cooked too, but feel a little more challenging to digest, whereas the young greens cook down super soft kind of like spinach.

A word on the “aggressive” growth habit - this vine will become a “weed” if you plant it in a small, orderly garden. This is not the ideal place for it. But given room to grow, it is fairly easy to manage - you can mow down the edges of the planting to keep it from spreading endlessly. Because the stems and the leaves fully die back every winter, it will not strangle out trees or shrubs that it climbs over. And because it climbs using tendrils instead of vining around branches, it’s easy to pull it off of the things you don’t want it to grow over. I have grown potatoes and beans in cleared patches totally surrounded by passionflower. This requires a regular removal of the passionflower in the first half of the summer, but it’s a fairly quick and simple weeding job that leaves me with a bushel full of consumable leaves. The shoots stop coming up by the end of the summer and leave the cultivated patches mostly alone. Standing in those patches and hearing the loud buzzing on the insects darting all around is a special experience and I wonder if this is what gardening sounded and felt like in some more insect-filled past. 

On the NC State Extension website (https://plants.ces.ncsu.edu/plants/passiflora-incarnata/) I found a note listing this plant as having an “extreme flammability” rating. I assume this is due to the fact that it produces a large mass of light dead plant material come winter, and this should be taken into account when planting in areas prone to fire. In places where fire danger is generally low though, this same feature acts as an organic-matter builder as the dead leaves rot in place.

If you want to save your own seed - wait to collect the fruit until it has fallen off the vine and is almost verging on rotting - its outer skin turning yellow and getting thin and papery to the touch. Squeeze the fruit pulp and seeds into a bucket or bowl, add a little bit of water, stir well, and leave to ferment in a hot sunny place for a couple of days. Cover it to avoid attracting bugs. Wash and decant once the pulp is fully fermented and separated off the seed, dry the seed in the sun fully before storing away.

A note on the conflicting info about woodyness of the vine and the toxicity of the non-fruit parts of the plant - I suspect that this arises from confusion between the Pasiflora incarnata and the more tropical Pasiflora edulis. But even the latter has been cited as having popularly consumed leaves by the National Institute of Health (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7251050/). There have been a number of bioprospecting studies into P. incarnata as a verified “antioxidant,”(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9254093/) and a potential aspect in treatment for dementia, parkinsonism (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726187/), seizures (https://pubmed.ncbi.nlm.nih.gov/22107833/), and things like anxiety and depression (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766837/)

If you desire more info, this post from Chestnut Herbal School of Medicine (https://chestnutherbs.com/passionflower-ecology-cultivation-botany-and-medicinal-and-edible-uses/) has some interesting stuff about the botany aspects of the plant, the etymology of the name “Maypop,” and more.

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