Shrub · Passifloraceae
Passionflower
Passiflora incarnata
Give it full sun and room to roam, and the maypop climbs 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 grown for its wild, fringed flowers and the egg-shaped fruit that follows. It climbs by tendrils and can run 6 to 8 feet (183 to 244 cm) in a season, scrambling over fences, trellises, and anything else within reach. The flowers open from July into September, and where summers are long the maypop ripens to a soft yellow by fall.
This is a tough, easygoing plant once it settles in. It takes full sun or a bit of shade, shrugs off drought, and handles clay, loam, or sand without complaint. Its one demand is drainage, since wet feet over winter are what usually do it in.
The vine earns its keep beyond the flowers. It is a larval host for fritillary and zebra longwing butterflies, so chewed leaves in summer are the plant doing its job. The trade-off is its drive to spread, sending up new shoots from the roots well away from where you set it.
Care
The short version: full sun to part shade, average soil that drains well, and a deep but infrequent drink once established. Give it a strong support to climb and the room, or the containment, to handle a vigorous spreader.
Light
Passionflower flowers best in full sun but takes part shade in stride. The more sun it gets, the more bloom and fruit you see, so give it the brightest spot you can spare.
Water
Keep it on average, medium moisture while it establishes, watering roughly every 7 to 14 days and letting the top half of the soil dry between drinks. Once settled it turns drought tolerant. Steer clear of wet, poorly drained ground, which rots the roots, especially over winter.
Soil
This vine is not fussy about soil and grows in clay, loam, or sand alike. What it must have is good drainage, since standing water is its main weakness.
Temperature
It is remarkably hardy, taking cold down to about -20°F (-29°C) and heat up to 100°F (38°C). In the colder end of its range the top dies back in winter and the roots resprout come spring.
Humidity
Ordinary outdoor humidity suits it fine, with no number to manage. Airflow and drainage matter more than any moisture in the air.
Feeding
Feed with a balanced general-purpose fertilizer two or three times across spring and summer. That is plenty, since an already vigorous vine pushed harder only grows ranker.
Pruning
Expect 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 cut away the dead growth and let the spring resprouts take over.
Repotting
In a pot the plant rarely needs repotting. Move it up only when roots fill the container, escape the drainage holes, or growth stalls in cramped quarters.
Size & spacing
A single season can carry the vine 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 if space is tight.
When to plant
Passionflower runs on warm-season time and needs frost behind it before it moves. Start seed indoors in late winter to early spring, set plants out in spring once the cold has passed, 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 trouble traces back to one of two things: a vine that spreads more than you bargained for, or roots sitting in water. Read the early signs below and match them to what you see. Some of it, like caterpillar-chewed leaves, is the plant working exactly as it should.
Wilting and yellowing in soggy, cool weather
Sitting water is the enemy here, and root rot sets in when the soil stays waterlogged, most often over a cool, wet winter. Check the roots, which turn dark, soft, and mushy once they go. Stop watering until the ground dries, improve the drainage or move the plant, and work organic matter into heavy soils so water can run 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
No regrowth in spring after a hard winter
In a borderline zone this comes down to cold injury, since the plant is not reliably hardy through USDA Zone 5. The roots simply fail to resprout in late spring after a tough winter, often where they had no mulch or shelter. Mound mulch over the crown before the cold arrives, plant against a south-facing wall, or grow it in a pot you can move 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
New shoots erupting far from where you planted
Passionflower spreads underground through root suckers and runners, sending up fresh vines well away from the parent. Trace the strays back to the lateral roots to confirm what you are seeing. Dig out the wanderers as they appear, or give the plant a contained bed, a large pot, or a root barrier 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
Leaves chewed up by orange-and-black caterpillars
This is the work of fritillary and zebra longwing caterpillars, and the passionflower is their host plant by design. Look for the spiny orange larvae and the butterflies feeding nearby. Leave them to it, because a healthy established vine grows right through the damage, and spraying would kill the very butterflies you are 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
Passionflower is not on the ASPCA toxic-plant lists, and the ripe maypop is good to eat. The caution is narrow: 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
The plant itself is rated non-toxic, but the leaves and unripe green fruit carry small amounts of cyanogenic glycosides. A cat that nibbles a little is unlikely to come to harm, though a big mouthful of foliage could bring on drooling or a mildly upset stomach.
Dogs Caution
A curious dog can chew the leaves without much trouble, since the plant is not on the toxic lists. Keep an eye on one that strips green growth or unripe fruit, where the cyanogenic glycosides can cause some stomach upset.
Horses Caution
Grazing the odd leaf poses little risk. The caution is for the foliage and unripe fruit eaten in quantity, which hold trace cyanogenic compounds that can leave a horse off its feed or queasy.
Rabbits Caution
Rabbits should not be turned loose on the leaves. The same cyanogenic glycosides in green growth and unripe fruit make the foliage a poor choice, so keep it out of the hutch.
Livestock Caution
Cattle, goats, and sheep can browse a stray vine without alarm, but a large feed of leaves or green fruit is best avoided because of the trace cyanogenic glycosides.
Birds Caution
Wild birds and poultry are drawn to the ripe maypop, which is fine. Steer them away from heavy feeding on the foliage and unripe fruit, where the cyanogenic compounds sit.
People Ripe fruit safe
The fully ripe maypop is good to eat, and the aerial parts have a long history in herbal teas. Skip the unripe green fruit and don't eat 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
Beyond the native maypop, a few related passionflowers turn up in gardens for their flowers, fragrance, or fruit. These are the ones worth knowing.
Passiflora caerulea (blue passionflower)
Its blue-and-white flowers and more evergreen habit make it hardier than the maypop in mild-winter areas.
Passiflora 'Incense'
This hybrid carries large, deep violet flowers with an intense fragrance.
Passiflora edulis (passion fruit)
Grown commercially for its edible passion fruit, this tropical species lacks the cold hardiness of the maypop.
How to propagate
Passionflower gives you three ways in, from a patient sowing of seed to the near-effortless splitting of the 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
Starting from seed takes patience. Sow indoors in late winter to early spring, or outdoors once frost has passed, and expect slow, erratic germination that can run several weeks. Soaking the seed first helps, and a young plant takes one to two seasons before it flowers.
DivisionEasy
Spring · One growing season
The vine's habit of throwing root suckers turns into an easy way to make more plants. In spring, dig up the suckers and separate them, and each one settles in over a single growing season.
Stem cuttingsModerate
Late spring to summer · Several weeks to root
Take softwood or semi-ripe cuttings from actively growing stems in late spring or summer. Given warmth and moisture, they root over several weeks into new plants.
Myths
The whole passionflower plant is poisonous and unsafe around pets and children.
Passiflora incarnata is not on the ASPCA toxic-plant lists, and the ripe maypop is edible. Only the leaves and unripe green fruit hold small amounts of cyanogenic glycosides, so the caution is about eating green growth in quantity, not about growing the plant nearby.
Caterpillars chewing the leaves are pests that need spraying.
The plant is a larval host for Gulf fritillary and other fritillary butterflies, so some leaf feeding is meant to happen. Spraying kills the butterflies the plant exists to support, and a healthy vine grows back through the damage on its own.