Shrub · Passifloraceae
Passionflower
Passiflora incarnata
Give it full sun and room to climb, and the maypop unfurls fringed flowers on tendrilled vines all summer long.
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 whose flowers open in an elaborate, fringed ring unlike almost anything else in the garden. Thread-thin tendrils curl and grip as the stems climb, stretching 6 to 8 feet (183 to 244 cm) in a season over fences, trellises, and whatever they can catch. The flowers appear from July into September, and behind them swells an egg-shaped fruit that ripens to a soft yellow by fall.
The vine wears its leaves in glossy green and clothes a support densely as it runs. It stands full sun or a little shade, rides out drought, and roots into clay, loam, or sand alike. What it will not forgive is wet feet through winter, since soggy ground rots its roots to a dark, soft pulp.
Look closely in summer and the foliage tells a second story. As a larval host for fritillary and zebra longwing butterflies, its leaves carry ragged, grazed edges and, often, bright spiny orange caterpillars at work. The vine answers the roaming instinct below ground too, sending pale suckers up from the roots far from where it began.
Care
The short version: full sun to part shade, average soil that drains freely, and a deep but occasional drink once established. Give the tendrils a strong support to grip and either room to spread or firm containment, since the roots wander.
Light
Passionflower opens the most flowers in full sun, though it takes part shade in stride. The brighter the light, the more fringed blooms and egg-shaped fruit it sets, so give it the sunniest spot you can.
Water
As it establishes, keep the soil at average, medium moisture, watering roughly every 7 to 14 days and letting the top half dry between drinks. Once settled the vine turns drought tolerant. Wet, poorly drained ground rots the roots to a dark, soft pulp, above all through winter.
Soil
The vine roots readily into clay, loam, or sand, with no fussiness over texture. What it insists on is free drainage, since standing water is the one thing its roots cannot survive.
Temperature
It weathers a wide swing, from cold near -20°F (-29°C) to heat around 100°F (38°C). Toward the cold end of its range the green top dies to the ground in winter, and fresh shoots push up from the roots come spring.
Humidity
Ordinary outdoor humidity is all its foliage asks, with no figure to manage. Airflow and drainage count far more than any moisture in the air.
Feeding
A balanced general-purpose fertilizer two or three times across spring and summer keeps it well fed. Pushed harder, this already vigorous vine only stacks on coarse, rank green growth.
Pruning
Plan to prune hard, since the fast, tendrilled stems overrun a support quickly. In cold zones the top dies to the ground each winter, so cut the dead, browned growth away and let the spring resprouts fill back in.
Repotting
In a pot the vine rarely needs repotting. Move it up only when roots pack the container, thread out the drainage holes, or growth stalls in cramped quarters.
Size & spacing
In one season the stems climb 6 to 8 feet (183 to 244 cm) tall with a spread of 3 to 6 feet (91 to 183 cm). Give the tendrils a sturdy trellis or fence to grip and room to reach, or pen the roots where space runs tight.
When to plant
Passionflower keeps to warm-season timing and holds until frost has passed before it stirs. Start the small seeds indoors in late winter to early spring, set plants out in spring once the cold has cleared, and watch the fringed flowers open from July into September, with the egg-shaped maypop 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 of what troubles a passionflower shows in one of two places: green shoots erupting far beyond their patch, or roots left standing in water. Read the early signs below against what the vine is showing. Some of it, like the lace-chewed summer leaves, is the plant doing exactly what it should.
Limp, yellowed leaves on a vine standing in sodden earth
Leaves lose their firmness and fade to sickly yellow while the stems go limp, all pointing to root rot in ground that stays sodden through a cool, wet winter. Lift a root and the rot shows plainly: once-firm tissue turned dark, soft, and mushy between the fingers. Hold off the water until the soil dries, sharpen the drainage or move the plant, and fork organic matter into heavy soil so it drains loose again.
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, brown crown with no fresh shoots by late spring
The crown stays bare and brown into late spring, with no green shoots breaking the soil, a sign of cold injury where the plant is not reliably hardy through USDA Zone 5. A hard winter kills the roots outright, most often where the crown sat exposed without a blanket of cover. Heap mulch over the crown before the freeze, set the plant against a warm south-facing wall, or keep it in a pot that can be carried 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
Slim green shoots breaking ground far from the parent vine
Slim green shoots break the soil surface at a distance from the parent, driven up by the root suckers and runners that snake sideways below ground. Follow one down and it joins the pale lateral roots fanning out from the crown. Lift the wanderers as they surface, or ring the plant with a bordered bed, a large pot, or a root barrier that pens those roots in.
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
Ragged, lace-like foliage crawling with spiny orange larvae
Ragged holes and stripped, lace-like leaves mark where fritillary and zebra longwing caterpillars have grazed, and this vine is their host by design. The larvae give themselves away as bright, spiny orange bodies inching over the foliage while the butterflies drift close by. A settled, healthy vine pushes fresh green growth faster than they can strip it, so no spray is warranted; one would only clear the butterflies away.
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
Passionflower is not on the ASPCA toxic-plant lists, and the soft-yellow ripe maypop is good to eat. The caution is narrow and physical: the green leaves and the hard, unripe green fruit hold small amounts of cyanogenic glycosides, so keep pets, livestock, and children from eating that green tissue in any quantity.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Caution
The plant itself rates non-toxic, yet the green leaves and the hard, unripe green fruit carry small amounts of cyanogenic glycosides. A cat that takes a single leaf between its teeth is unlikely to suffer, while a full mouthful of that foliage can bring on drooling or a mildly upset stomach.
Dogs Caution
A dog can crush a leaf or two between its jaws without harm, since the plant sits off the toxic lists. Watch the one that shreds green growth or bites into the firm green fruit, where the cyanogenic glycosides can turn the stomach.
Horses Caution
A single grazed leaf carries little risk. The caution rests on the green foliage and unripe fruit taken in quantity, whose trace cyanogenic compounds can leave a horse off its feed or queasy.
Rabbits Caution
The green leaves are a poor choice for rabbits. The same cyanogenic glycosides sit in the soft new growth and the hard unripe fruit, so keep the plant out of reach of the hutch.
Livestock Caution
Cattle, goats, and sheep can strip the odd leaf from a stray vine without alarm. A large feed of leaves or green fruit is what to avoid, for the trace cyanogenic glycosides packed in that green tissue.
Birds Caution
Wild birds and poultry go for the ripe, soft-yellow maypop, which is fine. Keep them from heavy feeding on the green leaves and the firm unripe fruit, where the cyanogenic compounds concentrate.
People Ripe fruit safe
The egg-shaped maypop, ripened to a soft yellow, is good to eat, and the aerial parts have long steeped into herbal teas. Pass over the hard green fruit and leave the leaves off the plate, 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
The maypop has close cousins whose blooms shift the palette, from blue-and-white flowers on an evergreen frame to deep violet petals carrying a heavy perfume. Each one wears the fringed passionflower form with its own look and habit.
Passiflora caerulea (blue passionflower)
Its flowers ring the center in bands of blue and white, and its more evergreen foliage carries it through mild-winter areas hardier than the maypop.
Passiflora 'Incense'
This hybrid opens large flowers in a deep, saturated violet, and they give off an intense fragrance.
Passiflora edulis (passion fruit)
Grown commercially for its edible passion fruit, this tropical species lacks the cold hardiness the maypop carries.
How to propagate
Passionflower offers three ways to raise more, from the patient sowing of its small seeds to the near-effortless splitting of the pale suckers it throws 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 calls for patience. Sow indoors in late winter to early spring, or outdoors once frost has passed, and expect the small seeds to break ground slowly and unevenly across several weeks. Soaking them first coaxes them along, and the young vine needs one to two seasons before its first fringed flowers open.
DivisionEasy
Spring · One growing season
The pale suckers the vine throws off its roots make division the simplest route. In spring, lift those rooted shoots and pull them apart, and each one takes hold over a single growing season.
Stem cuttingsModerate
Late spring to summer · Several weeks to root
Cut soft, green softwood or firmer semi-ripe pieces from actively growing stems in late spring or summer. Held warm and moist, they push roots over several weeks into new plants.
Myths
From its tendrils to its fruit, the whole passionflower is toxic and a hazard to children and pets.
Passiflora incarnata is absent from the ASPCA toxic-plant lists, and the soft-yellow ripe maypop is edible. Only the green leaves and the hard, unripe green fruit hold small amounts of cyanogenic glycosides, so the caution falls on eating that green tissue in quantity, not on growing the plant nearby.
The spiny caterpillars stripping the leaves are an outbreak that must be knocked down with pesticide.
The vine is a larval host for Gulf fritillary and its relatives, so the chewed, lace-edged leaves of summer are meant to be there. Spraying strips away the butterflies the plant feeds, while a healthy vine simply throws fresh green growth over the gaps.