Passiflora caerulea – Passion Flower

The Passion Flower is an impressive climber with unusual and interesting flowers. Blue and white flowers are most common but there is a red-flowered variety. The leaves are smooth and clear green in colour ; they usually consist of five pointed fingers, splayed.

There are hundreds of species of passion flowers, but only two are hardy enough to be grown outdoors in this country, and even they are confined to sheltered sites in the south and south-west. There, frost may cut the top to the ground, but it usually grows back in the spring.

All the passion flowers are more or less tender, but Passiflora caerulea is near enough hardy to be worth planting out of doors in sunny, sheltered places. It is a very vigorous climber which is capable of growing 15 ft. even after it has been cut to ground level by winter frost. The bluish-white flowers look a little like those of a clematis, but with a central corona of filaments which are in three concentric zones of blue, white and purple in the common variety but are all white in variety Constance Elliott. Both plants climb by tendrils so require wires, trellises or something similar to which to cling.

Natives of Central and South America, the passion flowers are vigorous evergreens, climbing by coiled tendrils which will cling to anything. The outdoor varieties produce their unusual flowers from June to September. P. caerulea (the blue or common passion flower) is the one most often planted in this country. It climbs to about 7.6m (25 ft). The species flowers are blue, purple and white, but there is a cultivar, ‘Constance Elliott’, which is white, and slightly hardier than the blue variety. P. umbellicata grows to 6m (20 ft), and has smaller, brown/purple flowers, geneally producing more of them than P. caerulea.

 

Passiflora caerulea - Passion Flower

Temperature:

  • Minimum winter 5 °C (41 °F)
  • In summer it may be stood out of doors

Soil: A soil-less compost. They succeed best in fertile, well-drained soils. Frost-damaged growth should be cut out in spring at which time any stems that threaten to grow too far can also be shortened.

Where to position: In plenty of light; it stands full sun. Indoors it dislikes a dark, draughty spot.

Watering requirements: Plenty of water in a well drained soil. Spraying is not necessary and there are no humidity requirements.

General care:

Find a sheltered site, preferably with full sun. Plant in ordinary garden soil when danger of frost has passed, and while the plant is young give it winter protection with bracken, straw, glass or plastic sheeting. Help the young plant to dimb by tying it to a trellis or mesh until it has started to pull itself up. Confine pruning to tidying up and removal of weak growth. Propagation: Take semi-ripe cuttings in summer and root them in pots of 50-50 peat and sand mixture, or grow from seed, germinating at a temperature of 21°C (70°F) and planting out in May after hardening off.

Don’t allow the temperature to drop below 5 °C (41 °F) in winter or next season’s flowers will be affected. Feed with very weak liquid fertilizer weekly in the growing season.

Rest: The plant rests in winter. Reduce watering, keeping soil only just moist until buds begin to swell, then slowly increase water. Feed when growing well.

 

When it looks sick:

  • A dull, drab and budless condition: It almost certainly needs more light. It may also be in a draught. Both conditions must be rectified.
  • Yellowing leaves : Indicates over-feeding which should be stopped. Water with soft water.
  • Drooping leaves : Check soil condition. It will probably be dry. If it is not then drainage is suspect and the plant may need re-potting.
  • Aphids : check regularly.

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