Exotic Passion Flowers look as though they would be tropical plants, but they can actually be grown almost anywhere, including much milder areas. You may even find these delicate vines growing along the side of the road. Some passion flowers species are becoming invasive in warmer climates.
The genus Passiflora contains over 400 species, so the common name Passion Flower can be a bit confusing. To muddle matters further, most are vines, but some are shrubs, annuals, perennials, and even trees and some also produce edible fruits. What they all share are exotic flowers that only remain open for about 1 day.
- Flowers: They have a wide, flat petal base with 5 or 10 petals in a flat or reflex circle. The ovary and stamens are held atop a tall, distinctive stalk which is encircled by delicate filaments. The stigmas start out high above the anthers and slowly bend backward for easier pollination. Colors include: blue, purple, pink, white and red.
- Foliage: The most commonly grown forms are vines that climb and cling by tendrils. The leaves are alternate and either lobed or ovate.
Passion Flower, Passion Vine, Maypop, Granadilla
USDA Hardiness Zone
Hardiness will depend on the variety of passion flower you are growing, but most are reliably perennial in USDA Hardiness Zones: 6-10.
Again, the mature size will vary with the type of passion flower you are growing. Most of the passion flower vines grow about 15-30 ft. (4.5 - 9 m) x 6-8 ft. (2-2.5 m)
To keep your passion flower vines healthy and blooming, plant them in full sun to partial shade. In Extremely hot climates, some afternoon shade is appreciated.
Most passion flowers grown in gardens will repeat bloom from mid- to late summer.
Design Tips Using Passion Flowers
Although passion flowers are native in many regions of the Southern U.S., they can become a nuisance, to the point of being invasive. Check with your local Cooperative Extension or DEC to see if you should avoid passion flowers altogether or if certain species are preferable.
A lot of gardeners prefer to grow their passion flowers in containers. Passion flowers grow quite happily in a pot and you have the convenience of being able to move them to a sunnier site or even bring them indoors for the winter. Plus, it limits the spreading by rhizomes.
Suggested Passion Flower Varieties
- Passiflora alata "Ruby Glow" (Fragrant Granadilla) - 4-inch flowers with cranberry petals and rich purple filaments. Very fragrant.
- Passiflora edulis - The species usually grown for the edible passion fruit. There are two types of passion fruit. A small, purple fruit and a larger shiny yellow-orange fruit (Passiflora edulis flavicarpa).
- Passiflora incarnata (Maypop) - A subtropical passion flower native to the southeastern U.S. Passiflora incarnata is also used medicinally.
Passion Flower Growing Tips
- Sun: Passion flowers need at least 4 full hours of sunlight a day; more in cooler climates and some partial shade in the hottest areas. Plants may need winter protection in Zone 6. In zones cooler than zone 6, they will be winter-killed, unless you bring them indoors.
- Soil: The soil should be well-draining, but rich. Passion flowers grow and bloom best when the soil is kept moist. They do not handle drought well. Soil pH can be in the neutral range, anywhere from about 6.1 to 7.5.
- Planting: The addition of compost to the planting hole will help retain moisture. Some type of support is needed for the vines to grow on. It can be a trellis, a structure or even another plant.
Growing Passion Flower from Seed
To save seed, allow the fruits to ripen completely. Open the pods and remove, clean and dry the seeds before storing. If you are saving seed from hybrid varieties, remember that they will not grow true from seed. Expect some surprises.
Passion flowers seeds can be slow to germinate. Start seed by soaking for 1-2 days in warm water. Viable seed will sink to the bottom of the glass. Floating seeds can be discarded.
Start seed in a damp potting mix. Place seed on the surface of the soil and pat down, but don’t cover. They need to be exposed to light, in order to germinate. Place the pot in a plastic bag and seal to retain moisture. If you can provide bottom heat to the pot, you’ll have a better chance of sprouting. A heat mat or even the top of a refrigerator should work.
It can take weeks or months for passion flower seeds to sprout. Keep the soil moist at all times. When sprouts do appear, keep them out of direct sunlight until there are true leaves and don’t handle the plants until they are large enough to transplant, with several sets of leaves.
To Grow Passion Flower as a Houseplant
Provide bright, indirect sunlight, but keep out of drafts. Minimum indoor temperature is about 50 F. If you are bringing your passion flower indoors for the winter, it will probably go semi-dormant and look less than ideal, but it should perk up again in the spring.
Caring for Passion Flower
Passion flowers are low maintenance during the growing season and do not need to be deadheaded. Pruning is basically done to keep the size in check, to remove dead wood and to make the plant fuller.
Some vines will not need any pruning, but pruning will result in a fuller plant. Pruning can be done in late winter or early spring. In cooler climates, the vines may die back to the ground anyway.
To protect borderline plants during winter, stop feeding in late summer. Mulch the area around the roots, once the soil temperature drops, to prevent freezing and thawing throughout winter.
Problems & Pests of Passion Flower
- It seems the more tropical the climate, the more pests there are to attack passion flower. The plants have minimal problems. Insects pests could include scale, spider mites, and whiteflies.
- Leaf spotting is generally caused by a fungal disease. Remove affected leaves, to slow the spread, and treat with a fungicide if necessary.