Solanum betaceum aka Tamarillo

Solanum betaceum is known as tamarillo or tree tomato. It belongs to the nightshade family, Solanaceae. Its native range lies in southern tropical South America. Sources name Argentina, Bolivia, and Peru within its range. It grows at forest edges and in open mountain forests. People grow it for food across several warmer continents. The older name Cyphomandra betacea refers to the same species.

This fast-growing evergreen forms a shrub or small tree. It has an upright shape and can become bushy. The RHS gives garden heights of 13–26 feet [4–8 metres]. Its spread reaches about 8–13 feet [2.5–4 metres]. Useful Tropical Plants gives a broader height range of 7–23 feet [2–7 metres]. A short trunk supports thick side branches and large leaves. Its roots sit near the soil surface. The plant is short-lived and prone to wind damage. Its bold leaves give it value as a specimen plant.

Pink to lavender flowers appear from May through August. The flowers have scent and add colour to the plant. The species can set fruit through self-pollination. Insects and wind also help with pollination. Oval fruits may be yellow, purple, orange, or red. The RHS places fruit ripening in late summer and autumn. Seed-grown plants can start bearing in their second or third year. The flesh tastes tart, with a mild tomato-like flavour. People eat ripe fruit raw or cook it. It suits salads, soups, sauces, jams, and chutneys. The thick skin tastes bitter, so people remove it. Unripe fruit is slightly toxic.

Grow this tender plant in full sun with shelter. It needs warmth and moist soil that drains well. The RHS lists clay, loam, sand, and chalk as suitable. It also accepts acid, neutral, or alkaline soil. Chicago lists USDA zones 10–11; the RHS rates it H1B. In Britain, containers can spend summer outdoors. Move them under glass for the colder months. A greenhouse or conservatory also provides a growing space. Regular pruning is not needed. Reduce its size in autumn when needed. Seeds and softwood cuttings offer ways to raise new plants.

Pests include aphids, whitefly, and glasshouse red spider mites. Slugs, snails, and nematodes can also cause trouble. Fruit flies may attack the crop in some places. Powdery mildew can become a serious problem. Honey fungus occurs less often. The plant is also prone to cucumber mosaic and potato viruses.