i have been dreaming/planning to grow passionfruits for a few years now.
Im a full zone lower than you.
Unfortunatly if had no sucses yet with tasty fruits. If had plenty of flowers and untasty/inedible fruits though.
Ill post some flower pictures as proof at the end of the post.
There are 4 problems for me getting tasty passion fruits so far.
1- not all fruits are edible.
And not all edible ones tasty good.
Caerulea (-15c or 5 F) for example fruits well for me. Gets sweet and ripe. But has a “dusty” aroma to it.
2- Frost hardines. but especially tolerance of waterlogging/cold wind of mosty tasty edible species is low.
I have overwintered non frost hardy passiflora outisde sucsefully. even though we had freezes.
The trick is the microclimate. Plant them in well draining soil, out of direct wind. Ideally against a warm wall.
Also putting an upside down terracotta pot near the base like they do with climatis helps. (climatis to protect base against sun). Planting them on a slight hill if the soil isen’t well draining might also help.
Mulching well is usful to ofcourse, Also during growing season. Since passiflora has a shallow root system
3-length of growing season. Even some of the edible passiflora species that consistently survive your winters will never ripen fruit if the growing season is not long enough.
Mature plants usualy flower earlier and thus ripen earlier. On the other hand frost damaged plants usualy flower later. Depending on growing climate length, there is thus a difference between frost hardines for survival and frost hardynes for fruit production.
4 pollination. Although the flowers are attractive to both humans hummingbirds insects and basicly every one.
They do need cross polination. And most passiflora sold are clones (cuttings).
So usualy your gonna depend on another species or a hybrid to pollinate your edible vine.
Keep in mind tetraploid vines need a tetraploid pollinator.
Or you could grow a few from the same species from seed. Try and get a “pure seed source though” since some species (and the resulting hybrids) can be toxic. I would not eat the fruit from a hybrid passionvine without knowing that both parrents are off and edible species.
Things i want to try out
-grafting on P. Caerulea to increase hardynes. But mostly tolerance to soil moistnes in winter.
-growing on the ground or low trellis.
-growing in a low (1-2 foot tunnel)
-burring the vine in winter to keep more of it’s branches frost fee.
-try the things from this link https://www.passionflow.co.uk/hardy-passiflora/
-use this link to find approximate frost hardynes https://www.passionflow.co.uk/wp-content/uploads/2017/08/Rusticite-Hardiness-Passiflora-.pdf
-only eat ripe fruits from known edible species. Some(most) of the 500+ passiflora species are toxic https://www.passionflow.co.uk/edible-passion-fruit/
-growing them in a greenhouse if all else fails.
-conside triploid / tetraploid plants. https://www.passionflow.co.uk/passiflora-polyploids/
https://www.researchgate.net/publication/267154892_Investigation_of_Passiflora_hybrids_using_flow_cytometry
Some of the plants im going to try out for fruits. (if i can find em)
-passiflora Byron Beauty (tetraploid) . P. incarnata
x P. edulis bred by Robert Knight of
the USDA in 1979. I think specificaly to get a frost hardier fruit producing vine. Both parants are good for eating.
Passiflora 'Byron Beauty' | 'Byron Beauty' Passionflower Pas… | Flickr
-P. incarnata / P. cincinnata based tetraploids. like P. inspiration P. Temptation and P. Byte
https://www.passionflow.co.uk/passiflora-inspiration/
https://www.passionflow.co.uk/passiflora-byte-flower/
-P. Tucumanensis (used to be known as P. Naviculata. Somtimes is also a tetraploid version available of) can handle some frost and might have a earlyer ripening. Is supposed to be really tasty. Might be harder to get a good pollinator.
https://web.archive.org/web/20160714181114/https://www.passionflow.co.uk/passiflora-tucumanensis.htm
-P. Guglielmo Betto (incarnata X Tucumanensis). Could not find info. But expect it to be edible/tasty. And have some frost tolerance.
-P. Fata Confetto (Guglielmo Betto x cincinnata Dark Pollen. Has really nice flowers and could be edible/tasty. Will be careful though.
Some reports of cincinnata being edible. And i asume gugliemo betto is also. Lot of assumptions though.
https://www.passionflow.co.uk/passiflora-fata-confetto/
-P. Actinia. Can handle some frost ans is supposed to have tasty fruits.https://www.passionflow.co.uk/passiflora-actinia/
-P. Elegans. Is verry similair to Actinia. Should be able to cros pollinate eachother
P. sidifolia is also similair to P actinia and elegans. But is supposed to be less frost hardy.
-P. Jutta is supposed to be frost hardy to some degree and has tasty fruits. Could never find someone with a plant for sale/trade though.
http://www.passiflora.info/jutta1.htm
-P. Incense (incarnata x cincinnata) . Might have tasty edible fruit. (careful though)
https://www.passionflow.co.uk/passiflora-incense/
pictures. First 2 can handle some frost (~-8 Celcius)
second 2 are for flowers and need to be overwintered inside.
