Exotic passionflowers may look like a tropical plant, but they can actually be grown almost anywhere, including much colder areas. In fact, you may even find these seemingly-delicate vines growing along the side of the road—some passionflower species are invasive in warmer climates.
The genus Passiflora is native to North America and South America and contains more than 500 species, so the common name passionflower can actually describe a number of different plants. Some are shrubs, annuals, perennials, and even trees; some also produce edible fruits. They all share exotic flowers that remain open for only about a day. The flower has a wide, flat petal base with five or 10 petals in a flat or reflex circle. Passionflowers are rapid growers and are best planted in spring or early fall while it's still warm. Where they are hardy, passionflowers are usually trained on a trellis, fence, or other vertical structures—in regions where they are not hardy, passionflower plants are often grown in pots and moved indoors for the winter.
|Botanical Name||Passiflora spp.|
|Common Names||Passionflower, passion vine, maypop, granadilla|
|Plant Type||Perennial vine|
|Mature Size||6–30 ft. tall, 3–6 ft. wide|
|Sun Exposure||Full sun, partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Flower Color||Purple, blue, pink, red, white|
|Hardiness Zones||5–9 (USDA)|
|Native Area||North America, South America|
Most species of passionflower are easy to grow—so easy, in fact, that they're sometimes considered invasive if left to their own devices. Typically, they should be grown in full sun to partial shade, in average soil that is well-drained. A sheltered location, such as against a garden wall, is recommended for many species, which can be damaged by major winds or harsh weather. If you are bringing your passionflower indoors for the winter, it will probably go semi-dormant and look less than ideal, but it should perk up again in the spring.
In addition to being a beautiful flowering vine for your garden, passionflower also has celebrated medicinal uses. Native Americans have long used passionflower to treat a variety of ailments, such as wounds, earaches, and liver problems, and it's also thought to be beneficial in treating insomnia and reducing stress and anxiety.
To keep your passionflower vines healthy and blooming, plant them in full sun to partial shade. In extremely hot climates, some afternoon shade is appreciated. Passionflowers generally need at least four to six full hours of sunlight a day (or more in cooler climates). If you bring potted specimens indoors for the winter, give them bright, indirect light and keep them away from drafts.
The soil you plant your vines in should be well-draining, but rich and moist. Soil pH isn't terribly important and can be in the neutral to acidic range, anywhere from about 6.1 to 7.5. The addition of compost to the planting hole will help provide nutrients, and mulching around the plant's base will assist in retaining moisture without having the plant become waterlogged. Typically, some type of support is needed for the vines to grow on—a trellis, a structure, or even another plant.
Passionflowers should be given a deep watering immediately after planting. Beyond that, they typically thrive with one or two waterings per week throughout their growing season. Make sure to provide about an inch to an inch and a half of water every week if there is no rain; they do not handle drought well.
Temperature and Humidity
Passionflower plants love warm weather and may need winter protection in cooler regions. In zones cooler than zone six, they often die in the winter unless you bring them indoors. Plant them in an area that's protected from wind, as a strong wind can damage stems and burn leaves. In addition, they do best in areas with moderate to high humidity.
Passionflower vines are heavy feeders and will benefit from a regular light application of balanced, general-purpose fertilizer with equal proportions of nitrogen, phosphorus, and potassium. Fertilize the plant before new growth emerges in early spring, and then repeat every four to six weeks until early autumn.
There are hundreds of varieties of passionflower, though they mostly differ in color and appearance, not care. Some of the most popular cultivars for landscaping and gardening include:
- Passiflora caerulea (blue passionflower)
- Passiflora coccinea (red passionflower)
- Passiflora incarnata (purple passionflower)
- Passiflora alata 'Ruby Glow' (fragrant granadilla)
Passionflowers are low maintenance during their growing season and do not need to be deadheaded. Pruning is done more to keep the size of the vine in-check, remove deadwood, and encourage fuller growth.
Pruning can be done in late winter or early spring—in cooler climates, the vines may die back to the ground anyway. These plants flower on new growth, so make sure to prune them before growth begins each spring in order to preserve the season's blooms.
How to Grow Passionflower from Seed
Most varieties of passionflower can be purchased as seedling plants. They can also be propagated from either seed, softwood cuttings, layering, or rhizomes.
- To save seed, allow the fruits to ripen completely. Open the pods and remove, clean, and dry the seeds before storing them. If you are saving seeds from a hybrid variety, remember that they will not grow true from seed, but will revert to the appearance of the parent species.
- Passionflowers seeds can be slow to germinate. Start your seed indoors by scarifying them and soaking them for one to two days in warm water. Discard any floating seeds, as these are not viable.
- Place the well-soaked seeds on the surface of damp potting mix, pat down, but do not cover since they need light to germinate. Place the pot into a plastic bag and seal to retain moisture. If you can provide bottom heat (via a heat mat) to the pot, you will speed up germination.
- It can take anywhere from 10 to 20 days for passionflower 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. Grow lights are your best light source during this stage of the process.
- Harden off the plant for 10 days to two weeks by slowly introducing it to outdoor conditions, extending the amount of sunlight it receives each day.
- Transplant once the plant gets large enough and possesses several sets of leaves.
- If direct-sowing seeds outdoors, wait until the danger of frost has passed and temperatures reach at least 55 degrees Fahrenheit.
Potting and Repotting Passionflower
Many gardeners prefer to grow their passionflowers in containers, where they will grow quite happily and offer you the convenience of being able to move them to a sunnier site or even bringing them indoors for the winter. Additionally, growing in pots prevents passionflowers from spreading uncontrollably.
To successfully pot your passionflower, use a potting soil rich in nutrients, and make sure the pot has several large drainage holes at its base. Keep the soil moist, but don't allow the roots to sit in water. Plants grown in containers will need more regular feedings since they are watered more frequently and nutrients typically rinse out as the soil drains. If you are bringing the plant indoors for winter, trim the stems down to one or two feet high before moving it.
Common Pests and Diseases
The more tropical the climate, the more pests there are to attack your passionflower plants, including scale, spider mites, and whiteflies. You can attempt to control any infestations with an insecticide.
Leaf spot is another potential issue and is generally caused by a fungal disease. To rid your plant of it, remove affected leaves to slow the spread and treat the plant with a fungicide if necessary. Root rot is also common in soils that do not drain well.