How to Grow Passionfruit
Passionfruit are semi-evergreen climbing perennial vine with edible fruit making it a welcome addition to the home garden. There are over 400 species of passiflora cultivated for their large, intricate, attractive exotic flowers ranging in colour from white and pink to red and purple. Many varieties have edible fruit but most are grown for ornamental purposes.
Young plants can be purchased from a garden store or grown from seed germinated at around 24°C (75°F) covered lightly with soil. Once established in the garden new plants can often be found growing from the seeds of fallen fruit.
Common Passion fruits types grown in the New Zealand garden include:
Black or Purple Passionfruit (P. edulis) is a very hardy vine that grows well in a warm, sunny or partially shaded site sheltered from the wind. P. edulis is a fast growing vine with showy medallion like flowers of purple, blue and white with radiating filaments and produce large numbers of egg shaped black or purple acid/sweet fruit.
Golden Passionfruit is a must for tropical fruit growers. A vigorous, fast growing tropical vine that produces loads of sweet fragrant flowers, followed by large, oval golden passiflora fruits with a delicious sweet/tart tropical taste. This variety of Passionfruit produces more and larger fruit than Passiflora edulis.
Banana Passionfruit is a hardy variety but the fruit is not as flavoursome as the black or Golden varieties. The fruit is yellow and banana shaped between 7.5cm (3 inches) to 10cm (4 Inches) long.
The secret to a good crop is the cater to their site and soil demands, feed them well and make sure they get plenty of water during the growing season. Passionfruit climb by tendrils and quickly cover an unsightly fence. Provide a support at least 1.5m to 1.75 m high such as a trellis, arbour, pergola or wire strung between posts where the breeze can pass through the foliage, rather than against a solid wall.
Passionfruit will tolerate most soil types. Grow in well drained soil to prevent problems with root rot. To test your site before planting apply this test. Dig a hole 30cm x 30cm x30cm and fill hole with water. Drainage is sufficient if the water has drained away completely in one hour. Soil can be enriched by adding compost and/or manure as well as a specially blended citrus tree fertiliser for the best results. If you have clay soil consider planting your vine in a raised bed enriched with plenty of well-rotted compost before planting.
Passionfruit are sub-tropical's from brazil so have poor tolerance to frost. Plant in a warm, sheltered, frost free position in moist soil and keep well watered until established. Young (and mature vines) can be protected from frost by covering with a frost cloth. Frost cloth lets in light, but keeps frost off plants and is very effective. It can be left on for a period of time or removed each day. Alternatively, consider planting your Passionfruit vine in a container that can be moved before frost sets in. If growing your Passionfruit vine in a container it will need a half wine barrel sized container when well grown.
Passionfruit are fast growing and need a lot of nitrogen for new growth and the flowers to form so require regular feeding - at least four times during the growing season. Avoid applying fertiliser in autumn as this will promote soft growth that will not be adequately hardened off before winter. Water well during the growing season and mulch annually with animal manure or compost, being careful to keep the stem area free. This will help conserve water during the hot summer months and helps with flower and fruit production. Ammonium Sulphate may also be beneficial in the warmer months of the first year of growth. Expect your first crop of fruit in about 18 months from time of planting.
Mature vines may need pruning annually to improve crop size. Most vines only last 5 or 6 years and sometimes up to 8 years before becoming exhausted so be sure to have a new one growing to replace the old one. Softwood and semi-ripe vine cuttings can be taken in late spring to autumn to replace older vines.
Pests and Problems
Snails, slugs and sap sucking insects can be a problem. Control any pests and diseases as necessary.
Whitefly is a global pest that can descend on outdoor plants during the summer months. Adults lay the eggs on the growing tips of plants on the underside of new leaves that hatch into whitefly scale a small larvae that sucks the sap out of leaves. The sugary sap from the leaves is excreted as honeydew in which black sooty mould can grow. Blast away adult whitefly with a hose and wipe infected leaves with a soapy rag at night. If the population is large use Pyrethrum spray or Neem oil on the underside of the leaves to control numbers and break the breeding cycle.
Companion plantings of French (targetes) Marigolds can be helpful. Marigolds are strongly aromatic plants with a pungent odour that hide the scent of the Passionfruit plant making it less attractive as a source of food or an egg laying site. Nausturtiums and Curry Plant (helichrysum angustifolium) are also a deterrent for whitefly in the garden.
Flowers fall off without forming fruit
One of the frustrating problems I have had this year has been due to the flowers falling off before the fruit formed due to a particularly rainy, windy start to the growing season. Passionfruit are insect pollinated by bees (and other insects) that collect the pollen and nectar that is high in sugar. Poor weather conditions such as wind and rain can cause a lack of bees out gathering pollens and nectars. Another contributing factor is that the pollen grains tend to burst in wet weather, so cool damp conditions inhibit flower production. As weather conditions improved the vine produced more flowers and eventually a good crop of fruit.
Spotty diseased leaves
In cool, wet conditions growth on the vine can slow down and disease symptoms become more obvious with a number of conditions causing leaf spot or worse still kill the leaves and shoots on what was otherwise a healthy plant.
Grease spot, is a bacterial disease that can affect leaves, stems and fruit. It is most active in autumn and winter but other diseases' can also cause spotting and leaf drop at other times. Grease spot on the leaves causes irregular olive-green to brown lesions, often surrounded by a light halo. In severe cases that plant can have severe leaf drop. The first signs of this infection on young stems are dark green, small, water soaked spots that quickly turn into brown spots. Eventually these spots can form right around the stem causing the shoot to die. Fruit infected drop prematurely and rots.
To help avoid fungal diseases don't water plants overhead during the summer months. keep the foliage as dry as possible. Prune out infected shoots as soon as they appear and clean up fallen leaves and damaged fruit regularly from under the vine. Regular spraying with a copper fungicide helps control many leaf spot diseases. Cover all the foliage with the spray for best protection.
Passionfruit are an excellent source of vitamin C, A and Potassium.
Passionfruit are delicious when eaten raw, added to fruit salad, on pavlova or ice cream, or used to make drinks, deserts, cakes and pies.