Passiflora caerulea (Blue Passionflower) Plant Guide

Passiflora caerulea, commonly known as the blue passionflower, is a captivating species that is full of character. Its distinct flowers and shiny rich green leaves make this ornamental plant a favorite among both horticulturists and hobby gardeners alike. 

From cottage gardens to pergolas, greenhouses, and arbors, the award-winning Passiflora caerulea will enhance any space with the exotic beauty of its flowers.

Origin and Characteristics:&Nbsp;Passiflora Caerulea

Passiflora caerulea

Native to South America, Passiflora caerulea is an herbaceous perennial belonging to the Passifloraceae family. 

The Passiflora genus is characterized by species that bloom intricate and often flamboyant flowers – the blue passionflower is no exception. Its blooms are 3 to 4 inches (7.5 to 10 cm) in diameter, with five whiteish petals and sepals sitting under a corona of blue and purple filaments. 

The reproductive structure, consisting of yellow stamens and purple stigmas, protrudes from the central point of the flower. It is typically in bloom from late spring through summer, followed by oval, egg-shaped deep orange fruits in late summer and early fall. 

Although the fruits are edible, they are not as tasty as the fruits of other species within the Passiflora genus. Blue passionflower leaves are glossy green and palmate-shaped with deep lobes.

Passionflowers are vigorous climbers. They use tendrils for support to grow up trellises or fences. Each twining tendril grows from a leaf axil or at the base of each leaf and will coil around any support structure it encounters. 

In temperate and sub-tropical climates (USDA hardiness zones 8 to 11), Passiflora caerulea grows as an evergreen, retaining its foliage throughout the year. 

In climates with colder winters (zones 7 to 1), the blue passionflower is likely to behave as a deciduous plant. Despite being native to sub-tropical and temperate regions of South America, it is a hardy plant and can survive even severe freezes as low as 5 °F (-15 °C).

Did you know… Passiflora caerulea plays a valuable role in pollination. Its nectar-rich, vibrant blossoms attract beneficial insects, including bees and butterflies, encouraging biodiversity in our green spaces.

Cultivating Blue Passionflowers

Passiflora caerulea garden

Passiflora caerulea prefers full sun to partial shade, 

so choose a location that receives at least 6 hours of sunlight daily. Blue passionflowers may benefit from partial shade during the intense afternoon sun in hotter climates. They thrive in fertile, well-draining, slightly acidic soil.

Blue passionflowers are vines that require a structure, such as fences or trellises, onto which they can grow. These structures can also be used to create sheltered and warmer microclimates.

In colder climates, passionflowers can be grown in containers, bringing the pot to a greenhouse or sheltered environment during harsh winters. 

It is essential to consider that pot-grown blue passionflowers will require more watering and fertilizing than those grown outdoors. 

In the ground, the plant develops a deep and extensive root system. The restricted root system in a container may result in less vigorous growth.

How To Care For Blue Passionflowers

Passiflora caerulea care

Watering

Passiflora caerulea prefers consistently moist but not waterlogged soil. Water frequently during the plant’s active growing season to support healthy growth and flowering. 

Ensure proper drainage in the planting area or container to avoid waterlogging. Add grit or sand to the substrate to improve permeability. For container plants, choose a pot with adequate drainage holes.

Fertilizing

Fertilizing Passiflora caerulea will provide the plant’s essential nutrients to maintain its health and encourage prolific flowering. 

Choose a balanced, water-soluble fertilizer that can be applied every 4 to 6 weeks during the growing season. During the dormant period, fertilizing will not be necessary.

Pruning

Although they do not require frequent pruning, passionflowers can be trimmed to manage size, prevent overcrowding, and encourage branching or new growth. 

The optimal time for pruning is either in late fall or early spring. Avoid excessive pruning during the active growing season, which may hinder growth and result in poor flowering. 

Cut back any mature or frost-damaged foliage to allow young, new growth to emerge.

To stimulate branching and lateral growth, the terminal buds of the plant can be removed. ‘Pinching’ will lead to a bushier overall appearance.

Overwintering

In colder climates, the foliage will die back during the winter and the roots will survive underground. For container-grown passionflowers, additional winter protection may be required. 

Consider relocating the pot to a warmer, more sheltered spot or wrap the pot with frost cloth or bubble wrap to protect it from severe winter weather.

Propagating Blue Passionflowers&Nbsp; &Nbsp; &Nbsp; &Nbsp; &Nbsp;

Passiflora caerulea can be successfully propagated by layering, stem cuttings, or from seed.

Layering

Layering is a great way to propagate climbing plants. This method encourages flexible stems to root while still attached to the parent plant. Layering is likely to produce early flowering offspring. 

The best time to propagate passionflowers by layering is during the active growing season, ideally in the spring or early summer.

  1. Select a healthy, young, and flexible stem.
  2. Choose a node that will reach the soil when the stem is bent toward the ground.
  3. Make a small incision on the stem just beneath the node using a sterile, sharp knife.
  4. Apply a rooting hormone to the wound (optional).
  5. Gently bend the stem down toward the ground, ensuring the wounded node is in contact with the soil.
  6. Secure in place using a U-shaped wire, paper clip, or light stone.
  7. Keep the soil around the node consistently moist to encourage rooting.
  8. Roots may take several weeks to a few months to develop.
  9. Once the layered stem has successfully developed a good root system, cut from the parent and transplanted into its own pot or garden bed.

Stem Cuttings

Propagating by stem cuttings produces offspring that can grow quickly and flower early. 

The following steps will help to create an optimal environment for successful rooting:

  1. Select healthy, non-flowering stems.
  2. Using a clean, sharp knife, cut a length of stem around 6 to 8 inches (15 to 20 cm) long. The cut should be just below the node.
  3. Remove any leaves from the lower half of the cutting.
  4. Apply a rooting hormone to the cut edge (optional).
  5. Plant the cutting into a well-draining potting medium suitable for propagation. Insert the cut end of the stem into the potting mix, around two nodes deep. Gently firm around the soil to hold the cutting in place.
  6. Water well.
  7. Create high humidity using a clear plastic bag or dome.
  8. Place in bright, indirect light.
  9. Keep the soil moist but avoid waterlogging.
  10. Roots may take a few weeks to develop.
  11. Once the cutting has successfully rooted, transplant it into a larger pot with all-purpose compost.

Seed

Blue passionflowers can also be grown from seed. However, seedlings may take several years to reach maturity and begin flowering.

  1. Collect seeds from mature passionflower fruits. Rinse thoroughly to remove any remaining pulp. Allow to dry.
  2. Once the seeds have dried, soak in warm water for 6 to 8 hours.
  3. Choose small pots with drainage holes and fill them with a well-draining seedling potting mix. Moisten the soil.
  4. Lay the seeds on the surface of the soil.
  5. Cover the pots with a clear plastic bag or dome to create a humid environment. Remove the plastic covering periodically to prevent fungal diseases such as damping-off.
  6. Place in a warm location with bright, indirect light.
  7. Seeds should take 8 to 10 weeks to germinate.
  8. Once the seedlings have grown a few true leaves, they can be transplanted into larger pots.

Blue Passionflower Cultivars&Nbsp;

Passiflora caerulea has several notable cultivars that offer alternatives to the classic blue passionflower. 

Here are just a few of the most popular, each with distinct characteristics:

  • P. caerulea ‘Snow Queen’: features flowers that are predominantly white or cream in color.
  • P. caerulea ‘Constance Elliott’: characterized by pure white flowers.
  • P. caerulea ‘Clear Sky’: features vibrant sky-blue flowers.
  • P. caerulea ‘Grandiflora’: blooms large flowers 4 to 5 inches (10 to 13 cm) in diameter.

Passiflora caerulea, the blue passionflower, is a captivating, unique flower, and ever-changing presence in a garden or landscape. 

Its intricate flowers are a haven for pollinators while twining vines contribute to its allure as a plant that interacts with its surroundings. 

Adaptable to a broad range of climates, Passiflora caerulea makes an enchanting addition to many spaces, and with the proper care, this elegant plant will flourish.

Stephanie Bartlett
Stephanie Bartlett
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Stephanie is a horticulturist specializing in interior plants. While living in Germany, Stephanie worked at a hydroponic herb farm, assisting in the research lab that developed new ways of growing. She gained her horticultural certificate from the Royal Horticultural Society in the UK and wrote for a German gardening publication. Her interests are in medicinal herbs, community gardens, and eco-therapy. Linkedin