Shrub · Passifloraceae
Passionflower
Passiflora incarnata
Give it full sun and a little room, and the maypop takes off fast, feeds butterflies, and flowers all summer.
Full sun
Every 7–14 days
USDA 5–9
6–8 ft · 1.8–2.4 m
Overview
Passionflower, or maypop, is a fast native vine people grow for its wild fringed flowers and the egg-shaped fruit that comes after. It climbs on its own tendrils, and in one season it'll cover 6 to 8 feet (183 to 244 cm), scrambling over fences, trellises, and pretty much anything nearby. The flowers show up from July into September, and where summers run long, that maypop ripens to a soft yellow by fall.
Once it's settled, this is a genuinely easygoing plant. It's happy in full sun or a bit of shade, it shrugs off drought, and it'll grow in clay, loam, or sand without a complaint. The one thing it really cares about is drainage, since soggy roots over winter are usually what does it in.
And there's more to it than the blooms. It's a larval host for fritillary and zebra longwing butterflies, so if the leaves get chewed up in summer, that's the plant doing exactly what it's supposed to. The catch? It loves to spread, sending up new shoots from the roots well away from where you first put it.
Care
The short version: full sun to part shade, average soil that drains well, and a deep but occasional drink once it's settled in. Give it a solid support to climb and either the room to spread or a bit of containment, since it's a vigorous spreader.
Light
Passionflower flowers best in full sun, but it'll take part shade in stride. The more sun it gets, the more flowers and fruit you'll see, so give it the brightest spot you've got.
Water
While it's getting established, keep the soil at average, medium moisture, watering about every 7 to 14 days and letting the top half dry out between drinks. Once it's settled, it turns nicely drought tolerant. Just keep it clear of wet, poorly drained ground, which rots the roots, especially over winter.
Soil
This vine isn't picky, and it'll grow in clay, loam, or sand just the same. What it can't do without is good drainage, since standing water is really its one weak spot.
Temperature
It's a tough one, handling cold down to about -20°F (-29°C) and heat up to 100°F (38°C). At the colder end of its range the top dies back in winter, but don't worry, the roots resprout come spring.
Humidity
Everyday outdoor humidity suits it fine, and there's no number to chase. Airflow and drainage matter way more than any moisture in the air.
Feeding
Give it a balanced general-purpose fertilizer two or three times across spring and summer, and that's plenty. Push an already vigorous vine harder and it just grows ranker.
Pruning
Plan to prune hard to keep this fast vine on its support and in bounds. In cold zones the top dies back to the ground each winter, so clear out the dead growth and let the spring resprouts take over.
Repotting
In a pot it rarely needs repotting. Move it up only when roots fill the container, slip out the drainage holes, or growth stalls in cramped quarters.
Size & spacing
In one season the vine can hit 6 to 8 feet (183 to 244 cm) tall with a spread of 3 to 6 feet (91 to 183 cm). Give it a sturdy trellis or fence and room to run, or contain the roots if space is tight.
When to plant
Passionflower runs on warm-season timing, so it wants frost out of the way before it gets going. Start seed indoors in late winter to early spring, move plants outside in spring once the cold's gone, and look for flowers from July into September, with maypop fruit ripening through late summer and fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring (6 to 8 weeks before last frost)
- Plant: Spring, after danger of frost has passed
- Harvest: Flowers July to September; egg-shaped maypop fruit ripens to yellowish in late summer to fall
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Most passionflower headaches come down to one of two things: a vine that spreads more than you counted on, or roots left sitting in water. Read the early signs below and match them to what you're seeing. And some of it, like caterpillar-chewed leaves, is honestly just the plant doing its job.
Sad, yellowed, wilting growth whenever the soil stays soggy
If the vine's wilting and yellowing in soaked ground, root rot is the likely answer, and it tends to hit over a cool, wet winter. Want to be sure? Dig gently and check the roots, since rotted ones go dark, soft, and mushy. Hold off watering until the soil dries out, sort out the drainage or move the plant somewhere better, and mix organic matter into heavy soil so water can actually get through.
Fix:
- Improve drainage or move the plant to a better-drained site
- Stop supplemental watering until soil dries
- Amend heavy soils with organic matter to improve drainage
Spring arrives and the vine just doesn't show up
In a borderline zone, a no-show spring usually means cold injury, because passionflower isn't dependably hardy through USDA Zone 5. What you'll notice is roots that just don't resprout come late spring after a rough winter, and it's almost always where the crown had no mulch or shelter. So pile mulch over the crown before the freeze, tuck it against a south-facing wall, or grow it in a pot you can shift somewhere sheltered when it gets really cold.
Fix:
- Mulch the root zone heavily before winter in cold zones
- Plant in a protected spot sheltered by a wall or structure
- In the coldest zones, grow as a container plant moved to shelter
New vines popping up nowhere near the original spot
Seeing vines pop up nowhere near where you planted? That's just passionflower traveling underground on its root suckers and runners. Follow one of those strays back and you'll hit the lateral roots that gave it away. Pull the wanderers whenever they show, and honestly, the easiest move is to box the plant into a bordered bed, a big pot, or a root barrier right from the start.
Fix:
- Dig out unwanted suckers as they appear
- Install a root barrier or grow in a contained bed or large pot
- Site it where it has room to roam or where mowing controls strays
Caterpillars munching the leaves down to the ribs
Those nibbled leaves are down to fritillary and zebra longwing caterpillars, and here's the thing: the passionflower is meant to feed them. Look for the spiny orange larvae with the butterflies fluttering close by. There's really nothing to do, since a healthy, settled vine grows right past the chewing, and a spray would just wipe out the very butterflies you're helping.
Fix:
- Tolerate the feeding, since this plant is intended to feed butterfly larvae
- Healthy established vines outgrow the damage
- Avoid insecticides, which kill the butterflies you are hosting
Toxicity
Here's the reassuring bit: passionflower isn't on the ASPCA toxic-plant lists, and the ripe maypop is good to eat. The one caution is narrow, since the leaves and unripe green fruit hold small amounts of cyanogenic glycosides, so keep pets, livestock, and kids from eating green growth in any quantity.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Caution
Good news first: the plant's rated non-toxic. That said, the leaves and unripe green fruit do hold small amounts of cyanogenic glycosides, so a quick nibble won't bother a cat, but a big mouthful of foliage might bring on drooling or a mildly upset stomach.
Dogs Caution
A dog can chew a leaf or two without much fuss, since this one isn't on the toxic lists. Just keep half an eye on any dog that strips the green growth or unripe fruit, where the cyanogenic glycosides can leave the stomach a little off.
Horses Caution
A grazed leaf here and there? No big deal. The worry's really about foliage and unripe fruit eaten in bulk, since the trace cyanogenic compounds can leave a horse off its feed or a bit queasy.
Rabbits Caution
It's best not to let rabbits at the leaves. Those same cyanogenic glycosides in the green growth and unripe fruit make the foliage a poor snack, so keep it well away from the hutch.
Livestock Caution
Cattle, goats, and sheep can browse a stray vine without any drama. What you'll want to skip is a big feed of leaves or green fruit, thanks to the trace cyanogenic glycosides they carry.
Birds Caution
Wild birds and poultry go for the ripe maypop, and that's perfectly fine. Just steer them off heavy feeding on the foliage and unripe fruit, where the cyanogenic compounds sit.
People Ripe fruit safe
The fully ripe maypop is great to eat, and the aerial parts have long shown up in herbal teas. Just pass on the unripe green fruit and don't munch the leaves in quantity, since both hold small amounts of cyanogenic glycosides.
Only fully ripe fruit is safe to eat. The leaves and unripe (green) fruit contain small amounts of cyanogenic glycosides, so unripe fruit and large quantities of foliage should not be eaten.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Past the native maypop, a handful of related passionflowers turn up in gardens for their flowers, scent, or fruit. Here are the ones worth knowing.
Passiflora caerulea (blue passionflower)
With its blue-and-white flowers and a more evergreen habit, it holds up to milder winters better than the maypop does.
Passiflora 'Incense'
This hybrid's the one to grow if you're after big, deep violet flowers with a really intense fragrance.
Passiflora edulis (passion fruit)
It's the tropical one grown commercially for edible passion fruit, though it can't take the cold the way the maypop can.
How to propagate
Passionflower gives you three ways in, from a patient sowing of seed to the almost-too-easy splitting of the suckers it throws all on its own.
SeedModerate
Sow indoors late winter to early spring, or outdoors after frost · Several weeks to germinate; one to two seasons to flower
Seed's the route that asks for a bit of patience. Sow indoors in late winter to early spring, or outdoors once frost's passed, and don't be thrown when germination comes in slow and uneven over several weeks. Soaking the seed first gives it a nudge, and a young plant takes one to two seasons before it flowers.
DivisionEasy
Spring · One growing season
Here's the easy win: the vine's habit of throwing root suckers basically hands you free plants. Dig up the suckers in spring, pull them apart, and each one settles in over a single growing season.
Stem cuttingsModerate
Late spring to summer · Several weeks to root
You can also snip softwood or semi-ripe cuttings off actively growing stems in late spring or summer. Keep them warm and moist and they'll root over several weeks into brand-new plants.
Myths
Passionflower is dangerous from root to tip, so families with pets or small kids should skip it.
Not really, though. Passiflora incarnata isn't on the ASPCA toxic-plant lists, and the ripe maypop is good to eat. Only the leaves and unripe green fruit carry small amounts of cyanogenic glycosides, so the caution's about eating green growth in quantity, not about having the plant around.
Those caterpillars gnawing the foliage are trouble and need a dose of bug spray.
Skip the spray. The plant's a larval host for Gulf fritillary and other fritillaries, so a bit of leaf feeding is exactly what's supposed to happen. Spraying kills the butterflies the plant's there to feed, and a healthy vine just grows back through the damage anyway.