How to grow Passion Flower

Passion flowers look exotic, but in fact they are easy to grow, and Passiflora caerulea, commonly known as the Blue Passion Flower, is hardy with an abundance of showy flowers in the summer. The Blue Passion flower requires only a little attention and is a green wheelbarrow plant.  

The Blue Passion flower is illustrated in the first image, top left and this variety widely offered for sale on-line and in garden centres. A native of South America, it is popular, in part, because it is hardy ** H4 which means -5 to -10.  I have seen Passion flowers grown in colder, more exposed areas and it seems to survive lower temperatures if planted in the right place. 

However, Passion flowers grown in colder areas, shed most, if not all, of its leaves in winter, and are at best semi ever green in colder areas.  In a reasonably sheltered spot, planted in well-drained soil, a Passion flower plant should require no additional attention or care over winter. 

Because Passion flowers are quite vigorous, RHS has listed the climber as potentially a nuisance and it does appear on the list of garden thugs. However, since for most of us gardeners, the problem is getting things to grow, I would not be overly concerned with planting Passion flower, and it response well to pruning, see below.

The most universally hardy, easy to grow and widely sold is the Blue passion flower. The less hardy varieties, such as Passiflora caerulea 'Constance Elliott' P. violacea, illustrated center image, unless grown in a very sheltered part of the UK will need to be container grown and brought under glass over winter.

Plant Passion flowers in spring or early autumn when the soil is still warm, and the autumn rains will water the plant until it is well-established.  If planted in spring or summer, it will be necessary to ensure the plant has plenty of water until established, after which it will look after itself. An ideal planting place for a Passion flower is a sheltered spot, southwest or west facing, close to wall if possible to protect from cold winds and in well-drained soil which is on the moist side, not too dry. If the ground is too dry, or there are dry conditions it may be necessary to water Passion flowers.

Passion flowers grow best and produce the most flowers in full sun, when they may also produce fruits in form of orange /yellow oval fruits.  Hardy Passion flowers will survive most of our winters, but in colder areas the plant will need protection such as a mulch to the roots, or even a hessian cover during the coldest months. Passion flower will grow in any soil, alkaline or acid, and in moist soil provided it is well drained.

Passion flowers require little or no maintenance and can be vigorous growing up to 8-12 meters. They can be grown in a container, but will require a largish container given they are a vigorous climber. Also, by necessity, the more tender varieties will need to be grown in a container to bring under cover for winter.

Gardening advise often makes mention of growing passion flowers in a conservatory.  The problem is that many conservatories in the summer reach high temperatures, which makes it a hostile environment for most plants. (An exception are Pelargoniums which tolerate conservatory conditions.) Unless your conservatory is well-ventilated, cooled and with a good amount of shade it is likely to be too hot and bake most plants including passion flowers. 

Passiflora caerulea 'Constance Elliott'  is hardy to H4 and is illustrated top centre. It will need a more sheltered spot and is a little more tender than the blue variety.  It has lovely white flowers which have the additional benefit of being scented. It will need winter protection.

The third image on the right, P.violacea is more tender still and will only withstand temperatures down to 1.C and will need glass or greenhouse protection over winter.

The Latin name for Passion flower, is Passiflora, so called after the Passion of Christ.  It is said that the stigmas and anthers represent the nails on the cross and the wounds. 

There are lots of attractive climbing plants to choose from for your garden. For more  information, images, and growing advice about climbing plants. 

Passion flower does not require routine pruning, although it will benefit from training to a fan shape rather than letting the tendrils determine the growth, which may end up looking untidy. P.caerulea, the most commonly grown, can be vigorous, and over time outgrow its allotted space or become untidy. Passion flower can be pruned after flowering to keep in shape or in the spring, the latter may result in reduced flowering that year.

Passion flowers have tendrils, which means it is self supporting and it will climb and twine. However, in common with many tendril plants, it can get into a tangle and it is best trained so the branches and flowers are spaced out. A trellis is ideal for a Passion flower to catch onto. 

When first planted, to get the passion flower to grow into a good shape, take 3-5 strong stems and train them with at least 2 stems running laterally. If you need to prune it, do so after flowering, which will be early Autumn time cutting back to a neat framework of buds.

You can hard prune a Passion flower if it becomes overgrown, and this is best done in the Spring. You can cut back harder, 30-60cms from soil level. It's vigorous and will grow back producing lots of new shoots which are best then fan trained to keep it in shape.

Updated 14.08.2023