Passionfruit, also called Granadilla

Passiflora edulis.

Origin:

Native to southern Brazil. There are two basic forms, P. edulis (purple passionfruit, PP) and P. edulis f flavicarpa (yellow, YP), and from these many hybrids have been produced.

Climate:

They grow well in sub-tropical and in elevated tropical areas where temperatures are not too low; YP is the more tropical of the two. Precipitation of 750-1250mm pa is best; if not well-distributed then irrigation will be required to sustain soil moisture and vegetative growth and production. Ideal temperatures are 20-25°C and tolerance of drought and frosts is low.

Plant Description:

Passionfruit are hexaploid, vigorous perennial herbaceous or woody vines up to 15m long, usually with axillary tendrils. The large tri-lobed alternate leaves have serrate margins. PP and YP have unbranched green and red-purplish tendrils respectively. They are not long-lived plants, with full production of PP for only 3-4 years.

Relatives:

Passifloraceae Family. Passiflora is a genus of about 500 species of flowering plants, many of which have beautiful, ornamental flowers. Only about a dozen species produce edible fruits, including Banana Passionfruit, Giant Granadilla and Sweet Granadilla.

Soils:

Fertile soils, pH 5-5-6.8, that are well-drained with high moisture retention are best. However, they can tolerate a wide-range of soil types. Mulching in sandy soils assists retention of water and nutrients.

Propagation:

Easily done with seeds, cuttings, air-layers and by grafting. However, as many superior passionfruit cultivars are hybrids, their seedlings will have variable characteristics compared to the parent, so named cultivars are best propagated vegetatively. Seedling YP are widely used as rootstocks in grafted plants as they are vigorous and resistant to root and stem rots and nematodes.

Cultivars:

Some cvs that can be sourced here are Panama Red, Panama Gold, Sunshine Special, Supersweet, Misty Gem, E-23 and Lacey. Sunshine Special is propagated by cuttings and doesn’t have a suckering problem as with many grafted plants; it also has good fruit set without any need for hand-pollination. The Panama varieties are more suitable for warmer areas north of Perth.

Flowering and Pollination:

Single hermaphrodite flowers can potentially form in each leaf axil. They are showy, 6-9cm diameter, with 5 sepals, 5 white petals forming a tubular calyx surrounded by a thread-like crown in the centre. The five stamens unite as a stalk bearing the superior ovary with 3 horizontal styles. Flowering can occur for much of the year in warm climates. They open in the morning and bees are the main pollinators. The most effective time for pollination is when the styles are curved towards the anthers. Rain at flowering time bursts pollen grains and may also interfere with bee activity. PP and hybrids are self-compatible but YP requires cross-pollination.

Cultivation:

They are most productive in full sun but will tolerate some shade. Fertilizers are routinely applied as passionfruit yield is related to growth. Nevertheless, this needs to be balanced as too much growth fosters disease. When young, small monthly applications are given with larger, less frequent amounts given as the plant matures. Water stress may cause young fruits to drop.

Wind Tolerance:

Windbreaks are important if grown in exposed sites.

Pruning:

Vines are supported on trellising of some sort with horizontal leaders giving off many fruiting laterals that hang toward the ground (hanging curtain). When this stage is reached some growers only then prune laterals that may touch the ground, with replanting when the canopy becomes overly dense. Others thin periodically by cutting back laterals to 20cm long, encouraging new lateral growth and flowering.

The Fruit:

A many-seeded berry, round to oblong, 5-10cm long, with many brown or black seeds surrounded by juicy and tangy arils. The yellow through to red or black purple skin is smooth and can be paper-thin to 5mm thick. The edible pulp has a fragrant odour and delicate flavour. YP is an excellent source of vitamin A (carotenoids) and both forms contain 11-15% carbohydrates.

Fruit Production and Harvesting:

Fruit mature in 3-4 months depending on climate. Commercial fruit are picked but home growers can wait for fruit to fall, with regular collection to prevent spoilage. Fresh YP and PP can be stored for 1-2 and 4-5 weeks respectively in a crisper at 5°C.

Fruit Uses:

Passionfruit are mostly converted into juice and also eaten fresh. They find widespread use as a flavouring agent in yoghurt, ice-cream and fruit salads and are incorporated in many baked products. They are probably valued more for their unique flavour and aroma than for nutritional content. Yield of juice/fruit is 30-33% and 45-50% for YP and PP respectively.

Pests and Diseases:

Possible pests include - Medfly, scales, mealy bug, mites and nematodes; and diseases - septoria, alternata or brown spot, anthracnose, base rot, fusarium wilt, phytophthora blight, scab and woodiness virus. Birds are occasional pests.

Comments:

As fruit is borne on new growth, plants should be kept in an active growth state. The most suitable cvs for our climate are relatively self-fertile, producing heavy crops, but hand-pollination may be necessary for fruit set in others. Plants are not long-lived and the need for replacement should be anticipated.

Be wary of grafted passionfruits that are on P. caerulia rootstock (such as Nelly Kelly): this rootstock is exceedingly invasive, it suckers extensively and is hard to eliminate. Frequently, the graft fails and the rootstock takes over. It is easily recognised by its five-fingered leaf shape.

More info: Passionfruit - flowering and yield