Shrub · Passifloraceae
Passionflower
Passiflora incarnata
Give it full sun and room to run, and the maypop rockets up its support, 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 that puts on a show with wild fringed flowers and the egg-shaped fruit that follows. It grabs on with tendrils and climbs 6 to 8 feet (183 to 244 cm) in a single season, storming over fences, trellises, and anything it can reach. The flowers blaze from July into September, and where summers run long the maypop ripens to a soft yellow by fall.
Once it digs in, this vine practically grows itself. It thrives in full sun or a touch of shade, powers through drought, and takes clay, loam, or sand without missing a beat. The one thing it demands is sharp drainage, since wet roots over winter are the one thing that trips it up.
The real payoff runs deeper than the flowers. As a larval host for fritillary and zebra longwing butterflies, this vine turns a summer of chewed leaves into a butterfly nursery, which is half the fun of growing it. The trade is its appetite for spreading, sending new shoots up from the roots well beyond where it started.
Care
The short version: full sun to part shade, average soil that drains, and a deep but occasional drink once it is established. Hand it a strong support to climb and either room to run or firm containment, since this one spreads with real gusto.
Light
Passionflower flowers hardest in full sun, though it takes part shade in stride. Pour on the light and it answers with more bloom and more fruit, so hand it the brightest spot you have.
Water
While it establishes, keep the soil at average, medium moisture, watering about every 7 to 14 days and letting the top half dry between drinks. Once it settles it turns drought tolerant and coasts on little. Just keep it off wet, poorly drained ground, which rots the roots, above all over winter.
Soil
This vine grows in clay, loam, or sand without a fuss and never slows down. The must-have is sharp drainage, since standing water is the one thing that can stop it cold.
Temperature
It is a tough customer, shrugging off cold near -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, then the roots burst back with fresh growth come spring.
Humidity
Everyday outdoor humidity suits it fine, with no number to chase. Airflow and drainage matter far more than any moisture in the air.
Feeding
Hit it with a balanced general-purpose fertilizer two or three times across spring and summer, and stop there. Push an already vigorous vine harder and it just piles on rank growth.
Pruning
Get ready 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 the dead growth and let the spring resprouts charge back.
Repotting
In a pot it rarely needs repotting. Bump it up only when roots fill the container, burst out the drainage holes, or growth stalls in cramped quarters.
Size & spacing
In one season the vine can shoot to 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 where space is tight.
When to plant
Passionflower fires up on warm-season timing and wants frost behind it before it takes off. Start seed indoors in late winter to early spring, plant out in spring once the cold clears, and gear up 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
Nearly every passionflower hiccup traces to one of two things: a vine that sprints past its bounds, or roots left sitting in water. Scan the early signs below and match them to what the plant is showing. Some of it, like caterpillar-chewed leaves, is the vine firing on all cylinders exactly as it should.
Wilting, yellowing vines stuck in cold, sodden ground
A vine that wilts and yellows in soaked ground is fighting root rot, and it strikes when the soil stays waterlogged through a cool, wet winter. Dig in and check the roots, which run dark, soft, and mushy once they go. Turn it around fast: cut off the water until the ground dries, sharpen the drainage or shift the plant to a better spot, and dig organic matter into heavy soil so water drains straight 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
A bare patch where the vine should be come spring
In a chancy zone, a spring no-show usually points to cold injury, since passionflower is not reliably hardy through USDA Zone 5. Watch for roots that just will not resprout in late spring after a brutal winter, most often where the crown went bare. Get ahead of it: pile mulch over the crown before the freeze hits, plant it against a warm south-facing wall, or grow it in a pot you can whisk off to shelter in the coldest spots.
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
Vigorous young vines charging up far from the mother plant
Fresh vines shooting up across the yard? That is passionflower running underground on its root suckers and runners, and it means the plant is charging ahead. Track a stray back to the lateral roots and the mystery unravels fast. Dig the wanderers out as they surface, or better yet, set the plant into a bordered bed, a big pot, or a root barrier from the start and let it push all that drive into one spot.
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
Foliage stripped back by hungry orange caterpillars
Those chewed leaves are a win, not a worry, because fritillary and zebra longwing caterpillars are feasting and the passionflower was built to host them. Hunt for the spiny orange larvae and the butterflies working the vine nearby. Let them go to town, since a healthy, established vine powers right through the feeding, and any spray would knock out the very butterflies the plant is raising.
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
Good news up front: passionflower is off the ASPCA toxic-plant lists, and the ripe maypop is a treat to eat. The one caution stays tight, since the leaves and unripe green fruit hold small amounts of cyanogenic glycosides, so keep pets, livestock, and children from eating green growth in any quantity.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Caution
Great start: the plant rates non-toxic. Even so, the leaves and unripe green fruit pack small amounts of cyanogenic glycosides, so a quick nibble will not trouble a cat, while a big mouthful of foliage can spark drooling or a mildly upset stomach.
Dogs Caution
A dog can crunch a leaf or two and shrug it off, since this plant sits off the toxic lists. Just keep tabs on any dog that tears into green growth or unripe fruit, where the cyanogenic glycosides can rattle the stomach.
Horses Caution
A grazed leaf now and then barely registers. The real caution kicks in with foliage and unripe fruit eaten in bulk, whose trace cyanogenic compounds can leave a horse off its feed or queasy.
Rabbits Caution
Keep rabbits well off the leaves. Those cyanogenic glycosides in the green growth and unripe fruit make the foliage a bad pick, so keep the plant clear of the hutch.
Livestock Caution
Cattle, goats, and sheep can browse a stray vine and think nothing of it. Steer them off a big feed of leaves or green fruit, which carry trace cyanogenic glycosides.
Birds Caution
Wild birds and poultry make a beeline for the ripe maypop, and that is all good. Just keep them from hammering the foliage and unripe fruit, where the cyanogenic compounds sit.
People Ripe fruit safe
Dig into the fully ripe maypop with confidence, and know the aerial parts have long powered herbal teas. Skip the unripe green fruit and keep the leaves off the menu, 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 earn a spot in gardens for their flowers, fragrance, or fruit. Meet the ones worth knowing.
Passiflora caerulea (blue passionflower)
Its striking blue-and-white flowers and more evergreen habit push it through milder winters better than the maypop.
Passiflora 'Incense'
This hybrid throws large, deep violet flowers loaded with an intense fragrance.
Passiflora edulis (passion fruit)
Grown commercially for its edible passion fruit, this tropical species races ahead in warmth but cannot match the maypop's cold hardiness.
How to propagate
Passionflower hands you three ways to make more, from a patient sowing of seed to the almost-too-easy splitting of the suckers it flings up 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 is the long game, and it pays off. Sow indoors in late winter to early spring, or outdoors once frost clears, and hang tight through slow, uneven germination that can stretch several weeks. Soak the seed first to spur it on, and give a young plant one to two seasons before it bursts into flower.
DivisionEasy
Spring · One growing season
Here is the fun, fast one: the vine's knack for throwing root suckers hands you free plants for the taking. Dig up the suckers in spring, split them apart, and each one roots in over a single growing season.
Stem cuttingsModerate
Late spring to summer · Several weeks to root
Snip softwood or semi-ripe cuttings off actively growing stems in late spring or summer. Keep them warm and moist and watch them root over several weeks into brand-new plants.
Myths
The entire vine, flowers to roots, is poisonous and far too risky to grow where pets or kids play.
Not so, and that is worth celebrating: Passiflora incarnata is off the ASPCA toxic-plant lists and the ripe maypop is edible. Only the leaves and unripe green fruit carry small amounts of cyanogenic glycosides, so the caution lands on eating green growth in quantity, never on growing this vine nearby.
Caterpillars devouring the foliage are invaders that deserve a quick blast of pesticide.
Put the sprayer down, because the plant is a larval host for Gulf fritillary and its cousins, so leaf feeding is the whole exciting point. Spraying wipes out the butterflies the plant exists to raise, and a healthy vine bounces back through the damage without help.