Reviewed By DAN ORI
Dan has over 27 years’ under his belt caring for plants and gardens. Working as a Horticultural Instructor and Consultant, he draws on a diverse range of experience that includes working as a Head Gardener, Tree Surgeon, Garden Centre Trouble Shooter, and writer of academic papers. Dan has a Level 3 Diploma in Horticulture and is currently a candidate for the RHS’s most prestigious award – The Master of Horticulture.
Contributions From MYLES STEWART IRVINE
Myles is an expert grower of Passiflora who has been growing and breeding this unique plant for 35 years. He is the breeder of Riverside™ Passiflora and set up the site Passiflora Online in 2000, home to a series of journals edited by himself. Myles’ work has been recognised in The Guardian and he has established himself as one of the UK’s most reputable passionflower growers.
IN THIS GUIDE
You’ve probably heard of passion fruit, but what about passion flower?
Passion flower (Passiflora) is a flowering vine with hundreds of variants, one of which (P. edulis) produces the colourful, seed-filled passion fruits you might find in your fruit bowl.
All varieties of this striking vine display dark green leaves and distinctive, tropical-looking flowers, with flat, open petals, showy stamens and hair-like coronas.
Passionflower comes in many colours, including purple, pink and blue, and can add an ornamental, exotic look to your garden.
For this guide, we consulted Myles Stewart Irvine, an expert grower and breeder of Passiflora.
“I randomly bought a Passiflora ‘Amethyst’ from a garden centre in the late 1980s,” says Myles.
“That started my lifetime fascination with these exotic and extraordinary plants.”
Overview
| Botanical Name | Passiflora |
| Common Name(s) | Passion Flower |
| Plant Type | Climber |
| Native Area | Americas |
| Hardiness Rating | Varies by type |
| Foliage | Evergreen, simple leaves |
| Flowers | Showy flowers |
| When To Sow | April, May, September, October |
| Flowering Months | May, June, July, August, September |
| When To Prune | March |
Sunlight
Preferred
Full Sun / Part Shade
Exposure
Sheltered
Size
Height
8 – 12M
Spread
2.5 – 4M
Bloom Time
May – September
Soil
Preferred
Chalk, Loam, Sand
Moisture
Moist but well drained
pH
Any
Passionflower originates mostly from Central and South America, with the exact locale depending on the variety.1Passiflora caerulea. (n.d.). Kew Royal Botanic Gardens. Retrieved March 22, 2023, from https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:321949-2
Some species are also native to the lower areas of North America.2Passiflora incarnata. (n.d.). Missouri Botanical Garden. Retrieved March 22, 2023, from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=q280
“There are about 550-600 species, mainly climbing vines plus a few trees, as well as hundreds of hybrids,” explains Myles.
“As climbing vines, they grow chaotically, swarming over whatever they can. Out of this chaos, they produce the most amazing intricate flowers, some of which are incredibly perfumed.”
Two of the most well-known varieties are P. edulis, a tropical, perennial vine which produces purple and white flowers, as well as edible purple and yellow passion fruits, and P. caerulea, a deciduous or semi-evergreen climbing shrub, with blue flowers.
These varieties can grow to 1.5-8m in height respectively.
“The common Passionflower, Passiflora caerulea, has blue and white flowers and orange fruit later in the season,” says Myles.
“This is a great plant to start with, as it is not fussy about anything and is free flowering from May to October.
Passiflora flowers are very distinctive – they are approximately 10cm wide, with a flat petal base, protruding stamen, and colourful corona (delicate, hair-like appendages) between the flower’s corolla and stamen.
The flowers are extremely attractive to pollinators (they are great for encouraging butterflies into your garden), but usually, only remain open for a day.
Today, passion flower is also known as ‘Passion Vine’, ‘Apricot Vine’ and ‘Maypop’ – due to the fact that it usually flowers in May.
Habitat & Growing Conditions
The native habitat of passion flower stretches from southern USA, through Central America and down to Brazil in South America; some varieties are also found in South East Asia and Oceania.
Although it originates from warm climates, many varieties are hardy, and can do well in much milder climates, including the UK.
In some warmer areas, the plant can even become invasive.3Passiflora incarnata. (n.d.-b). Center for Aquatic and Invasive Plants: University of Florida. Retrieved March 22, 2023, from https://plants.ifas.ufl.edu/plant-directory/passiflora-incarnata/
Passionflower grows in anything from indirect to full sunlight; it favours a moist, fertile soil, with a neutral pH and adequate drainage and it does not like to be water-logged, as this can lead to wilting, fungus and root rot.
How To Grow Passion Flower
You can purchase passionflower seeds and seedling plants from garden centres, nurseries and online retailers.
The most popular species available in the UK is the hardy, blue-flowered P. caerulea – if you want another variety, you may need to shop around to find a specialist grower.
Growing From Seed
Growing passion flower from seeds is not the quickest or easiest option.
Seeds sprout best when they are fresh, and it is recommended to soak them overnight prior to planting, to break down the seed shell and assist with germination.
Even so, it can take seeds up to a year to sprout.
“Though growing from seed can be great fun, in practice the seeds are often slow to germinate, taking many months to do so – if they come up at all,” says Myles.
“The seedlings can be weak and variable too, and seed for sale may often be old or described incorrectly.
“So, it is far safer to pay more money and buy established plants from reputable suppliers, either garden centres or more specialist nurseries.”
Many garden centres and supermarkets will only sell passion flower in season, when the plant looks its best.
To purchase passion flower out of season, find a nursery that grows them outdoors, meaning the plant should be hardier, and able to withstand being planted in colder weather.
“There is only a limited range of hardy passiflora that do well in the UK climate outdoors year-round, but even then they will do best in more southerly areas,” Myles warns.
If you know someone with a passion flower, it is also possible to propagate them from cuttings or layered shoots.
Passiflora Care
Hardiness
It is important to note that the variety of passion flower you are growing will affect the way you care for it.
For example, P. caerulea is resistant to frost, so can be grown outside (although it may still require cover in winter).
“Another good option to grow outside is the purple-flowered Passiflora x violacea, which is an inter-species hybrid (a cross between) P. caerulea and P. racemosa,” shares Master Horticulturist Dan Ori.
Many other species are not hardy to freezing temperatures, and should be kept above 5°C, or, in the case of tropical varieties such as P. edulis, above 10°C.
These plants need to be brought inside during winter – make sure to research your chosen variant prior to purchasing, so you know of its specific requirements.
Preferred Aspect
“Bearing in mind that there are hundreds of different Passionflowers, some, of course, need specialist care,” Myles explains.
“However, those most widely available love a sunny, south-facing location, perhaps in thin beds hard up against a brick wall or in terracotta pots.”
If you’re growing your passion flower outside, always try to choose a sheltered spot, with either full or partial sunlight, avoiding areas that are entirely shaded.
Passionflower can also be grown in a sunny area indoors, or in a greenhouse – although some protection may be needed to avoid leaf burn in summer.
You can either plant it in your garden borders, or grow it in a container.
Growing passion flower in a container is advisable, as it means you can move it around, control the amount of sunlight it gets, and bring it inside to protect from frost.
It will also help prevent your passion flower from spreading and becoming invasive.
Soil Requirements
Depending on the variety, passion flower is generally a hardy plant, and will thrive in pretty much any soil type and pH.
It does, however, prefer its soil to be fertile – when planting in a container, do so in a high-quality, peat-free compost.
“They love a free-draining soil mix, so add rubble, sharp sand and horticultural grit as appropriate,” suggests Myles.
“They are also greedy feeders and, when growing at full speed, will benefit from a good general-purpose liquid or prolonged release fertiliser, especially when grown in pots.
“For the most part, I use chicken manure or seaweed pellets for my plants.”
Watering
As far as watering is concerned, you should keep soil moist throughout the summer growing season.
Do not allow it to dry out, but make sure it’s not waterlogged either – the soil should have good drainage.
“Over winter, the roots can easily rot,” says Myles.
“Even in summer, a thorough soaking weekly is better than daily.”
With this in mind, you should reduce watering during winter.
Support
“Passion flowers will want a trellis, wire or similar to climb up,” explains Myles.
“If you’re growing it in a pot, a tripod of 5-foot bamboo canes will do fine.”
You can encourage it to do so by using soft plant ties to attach the branches to the support, at regular intervals, whilst it’s growing.
Pruning
“In a tropical climate, you can prune passion flowers anytime and get away with it, but in the UK, it is best to leave as much greenery on them as possible to help them get through winter,” Myles shares.
“The time to prune is in late spring when regrowth has started.”
Trim back the growing shoots, to encourage the plant to branch at the base, and grow in a more attractive shape.
“Leave at least two long stems with leaves on until the whole plant has new growth,” says Myles.
“At that stage, you can then cut back the two long stems and the plant will be fine.”
This is also the time to start training your plant to grow along a fence or trellis, by tying its shoots periodically along the fence.
Once your passion flower reaches maturity, you should prune it every spring, to encourage flowering.
Take this opportunity to trim back any extended shoots, re-shaping it into your desired form.
If growing outside, you should also make sure to remove any limbs damaged by frost.
Common Problems
There are several problems that are common to passion flower.
Cucumber Mosaic Virus
One to watch out for is Cucumber mosaic virus (CMV), which can cause a mottled yellow appearance, stunted growth and a reduction or distortion of fruit.
Infected plants may need to be destroyed to prevent the virus spreading.
Pests
Passionflower is also susceptible to pests, including aphid, whitefly, red mite spider and mealybug.
This is particularly true if you are growing your plant in a greenhouse, as these pests favour a warm environment.
“Passion flowers are prone to spider mites and mealy bugs,” explains Myles.
“These are best treated by spraying or hosing down your plants with water daily, above and below the leaves.”
Check your passion flower regularly for signs of infestation.
Mould & Fungus
As with many plants, you should also watch out for any signs of a fungal infection – signs can include black patches and visible mould.
Help to avoid this by ensuring the plant is in full sunlight, and that you only water the soil at the base of the plant, not the leaves.
Other than these, the most common problems that affect passion flower are wilting, wind scorch and blackened leaves, which may be caused by harsh weather or winter frost.
FAQs
Why Is My Plant Failing To Flower?
You can encourage blooming with annual pruning, and by ensuring your passionflower has sufficient sunlight.
If your plant still doesn’t bloom, try adding a high-potassium liquid fertiliser to the soil once a week during the spring and summer months.
It is also worth noting that many passion flower blooms only last a day, so you will need to be present and check on the plant regularly if you don’t want to miss it!
Can You Grow The Flower From Cuttings?
Yes, you can grow passion flower from cuttings.
To do so:
- Use sharp pruners to take stem cuttings of around 15cm from the plant, early in the growing season.
- Remove the leaves at the bottom of the cutting, and dip the end in a rooting hormone.
- Place the cuttings 1–2cm into a potting mix, and keep them moist and warm, although initially out of direct sunlight.
After about a month, new roots should begin to take hold.
