Tamarillo

What is a tamarillo?

The tamarillo, also called tree tomato, is a small tree of the nightshade family, Solanaceae. That makes it a relative of the tomato and the potato, although it looks quite different: a slender, half-woody stem, an umbrella-like crown of large, soft, heart-shaped leaves and pendant clusters of smooth, egg-shaped fruit. Botanists today call it Solanum betaceum; in older literature it appears as Cyphomandra betacea.

The fruit is 5 to 10 cm long and 4 to 5 cm wide, pointed at both ends, and depending on the type purple, blood-red, orange or yellow. Inside, juicy flesh surrounds many small, dark seeds.

Origin and growth

The exact origin is uncertain. Julia Morton considers it probably native to the Andes of Peru, and probably also of Chile, Ecuador and Bolivia; it is widely grown in Colombia, Argentina and Brazil. In Ecuador it is cultivated at about 1,500 to 3,000 m, where days are mild and nights cool. From there it reached Central America, East Africa, India, Australia and New Zealand, where small-scale commercial cultivation began around 1920 and the name tamarillo was adopted around 1970.

The tamarillo grows fast and stays small, usually 3 to 5.5 m, rarely more. It is short-lived: Morton gives five to six productive years, or eleven to twelve with good nutrition. It starts bearing after one and a half to two years. Its roots are shallow and its wood is brittle.

Requirements

The tamarillo is a subtropical plant and does best where temperatures stay above about 10 °C. Frost of about -2.2 °C kills twigs and leaves of mature trees but not the main stem, while young plants die easily in their first winter. It needs fertile, light soil with perfect drainage: standing water for even a few days can kill it, and compacted, airless soil does not suit it. At the same time it cannot cope with prolonged drought and needs ample water in dry periods; Morton recommends mulch to hold moisture. Wind is its greatest enemy.

Fruit, use and harvest

The fruit ripens unevenly, so a tree is picked several times. Morton reports yields of about 20 to 30 kg per tree and year in Brazil. The skin is tough and bitter-tasting and is not eaten; the flesh is spooned out or the fruit peeled. It is eaten raw with sugar, juiced, cooked into sauces, chutneys and jams, or, as in the Andes, blended into a drink.

In the food forest

In a food forest the tamarillo belongs to the shrub layer, and its short life gives it a particular role. It fruits quickly, in the second year, while the long-lived trees around it are still small, and it makes way when they close their canopy. That makes it a plant of the early stages of succession, comparable to how syntropic agriculture uses short-lived species to bridge the years until the main trees bear. Neighbours protect it from wind; a permanent layer of mulch keeps its shallow roots cool and moist. When it is pruned or dies, its soft wood and large leaves return to the soil quickly.

In the Mediterranean climate

In southern Europe the tamarillo is a niche crop. On Madeira it is grown in small plantations, above all around Santana on the north coast and Camacha in the south, from about 300 to 400 m upwards. Its juice there goes into poncha, the island's traditional drink. For the Mediterranean proper, published experience is scarce. Two limits stand out: frost below about -2 °C in winter, and the long dry summer, which it does not tolerate without irrigation. A plant from cool Andean slopes is likely to appreciate light shade in the hottest hours and a sheltered, moist corner.

Where it feels at home, the tamarillo can spread: it is listed as a weed in New Zealand and South Africa and grows wild along rainforest margins in New South Wales. Birds carry the seeds. It is not on the EU list of invasive alien species. Whether it sows itself in a dry Mediterranean summer is not documented; harvesting the fruit and pulling stray seedlings keeps it under control.

Propagation and care

Tamarillos grow easily from seed or cuttings. Seedlings form tall, upright trees; cuttings give lower, bushier plants that suit windy sites better. Young plants are often tipped early to encourage branching. Pests include aphids and fruit flies, and powdery mildew is the most common disease.

How Terra Humana understands it

At Sa Medada the tamarillo is a plant of the beginning. It does not promise permanence, but quick fruit and soft biomass in the years when the young trees are still finding their place. Terra Humana uses vigorous species that are not on the EU list deliberately, as a method; with the tamarillo that means harvesting it attentively and keeping an eye on where its seeds go.