Dragon Fruit

What is dragon fruit?

Dragon fruit, also called pitaya or pitahaya, is the fruit of climbing cacti from the genus Selenicereus, until recently placed in Hylocereus. Unlike the familiar barrel cacti of the desert, these are plants of dry forests: their three-angled, jointed stems climb trees and rocks with aerial roots, and they can grow several metres long.

The best-known species, Selenicereus undatus, bears pink fruit with green-tipped scales and white flesh full of tiny black seeds. Red- and purple-fleshed fruit comes from related species and hybrids; the yellow pitaya, Selenicereus megalanthus, has a spiny yellow skin and particularly sweet white flesh. The flowers are among the largest of any cactus, white and fragrant, and open for a single night.

Origin and growth

The genus is native to Mexico and Central America; the exact native range of the cultivated species is blurred by centuries of planting. Today pitaya is grown across the tropics and subtropics, with large plantations in Vietnam, Central America and Israel.

As a cactus with crassulacean acid metabolism, pitaya opens its pores at night and loses little water during the day. The stems store water and serve as leaves. In cultivation the plant is trained up a post or frame and allowed to cascade from the top, where most flowers and fruit form.

Requirements

The University of Florida describes pitaya as a plant for frost-free areas. Prolonged temperatures below about -0.5 °C harm it, light frost injury heals quickly, and the plant copes with heat up to about 38 °C. Its growth optimum lies at about 18 to 25 °C. Intense sun burns the stems, particularly in dry air, so about 30 % shade is recommended at least in the first months; too much shade, on the other hand, reduces flowering. It needs a well-drained soil rich in organic matter and does not tolerate waterlogging. It is frugal with water, but needs regular moisture while flowering and fruiting.

Fruit, use and harvest

Fruit follows flowering in waves from summer into autumn. It is ripe when the skin has fully coloured. The flesh is eaten fresh, mild and refreshing in white-fleshed types, more aromatic in red and yellow ones, and used in juices, smoothies and sorbets. Some species and varieties are self-incompatible and fruit only with pollen from another genotype. Hand pollination in the evening or at dawn helps.

In the food forest

In a food forest pitaya belongs to the climbing layer. It can grow on a sturdy post, on a dry-stone wall or on a living tree, which is how it grows in the wild. Light shade from a nurse tree or a shade net protects the stems from summer sunburn, while enough light must reach the top of the plant for flowering. Because it needs little water, it fits well into dry gardens and sunny edges where other fruit plants would struggle.

In the Mediterranean climate

The longest Mediterranean experience comes from Israel. Since the 1990s Yosef Mizrahi's group at Ben-Gurion University has grown pitaya in the Negev, where it uses far less water than orchard trees but is generally grown under shade nets, because full sun damages the stems. In Sicily the University of Palermo has grown pitaya in unheated greenhouses under 30 % shade, with fruit from June to November and growth stopping as autumn cooled. In the Algarve, open-field trials have tested spacing and shading. Italian researchers see it as a possible new crop for the Mediterranean, limited by frost, high summer radiation and cool autumns.

There is also a caution. Selenicereus undatus is naturalised in Hawaii, where it smothers native vegetation, and in South Africa it is considered a growing invader of coastal forests. It roots from every stem fragment. It is not on the EU list of invasive alien species. In practice this means keeping it on its supports, not dumping prunings in the open landscape and watching for plants appearing where none were set.

Propagation and care

Pitaya is propagated almost entirely by stem cuttings, which root easily after the cut surface has dried for a few days. Seeds germinate readily but give variable plants. A firm support, light shade in summer, protection from frost and a few different varieties for cross-pollination are the basics.

How Terra Humana understands it

Pitaya is an experiment in the opposite direction from most of Sa Medada's fruit trees: a plant that saves water and suffers more from strong sun than from drought. Terra Humana sees in it a possible climber for walls, posts and the sunny edges of the food forest. Its invasive record elsewhere is part of the picture. Terra Humana deliberately works with vigorous species that are not on the EU list, as a method, and with pitaya that means keeping cuttings under control and watching what happens around it.