Lychee

What is a lychee?

The lychee is an evergreen fruit tree with a dense, rounded crown of glossy, pinnate leaves. Its fruit hang in loose clusters of a few to several dozen. Under the rough, red shell, which peels away easily, lies a white, translucent aril, juicy, sweet and slightly acidic, around a single smooth brown seed. The fruit must ripen on the tree; it does not ripen further after picking.

Origin and growth

The lychee comes from the lowlands of Guangdong and Fujian in southern China, where it grows along rivers and near the coast. From there it spread through South-east Asia, reaching Burma in the late seventeenth century and India a century later, according to Julia Morton. The oldest known treatise on the fruit dates from 1059.

The tree grows slowly. It can reach about 12 metres, but in gardens it is often kept at three to five metres. Trees raised from air layers or grafts bear after three to five years; seedlings often need ten years or more.

Requirements

Cold and the winter rest. Lychee needs a cool winter to flower and a frost-free one to survive. Young trees are damaged at about 0 to -2 °C, older trees at about -4 °C over several hours. Flower induction works best around 15 °C; long warm spells above 20 °C during winter suppress it.

Water. Established trees tolerate moderate drought, young trees need regular watering. A dry spell before flowering promotes bloom; while the fruit grows in spring and summer, the tree needs steady moisture.

Soil. Well drained, slightly acid, with organic matter. On calcareous soils the University of Florida warns of deficiencies in trace elements.

Light and wind. Full sun. Constant wind tears the leaves and stunts the young shoots, so sheltered sites are best.

Fruit, use and harvest

Lychees are eaten fresh, frozen, canned or dried. In Florida the harvest runs from mid-May to early July; in the Axarquía near Málaga it runs from August into September. Bees and flies pollinate the flowers, and the tree is a valued bee plant. Fruit should be picked fully ripe and eaten ripe; see the caution on unripe fruit above.

In the food forest

In a food forest the lychee belongs to the medium to tall tree layer. Its dense crown casts deep shade, so plants beneath it must tolerate shade or be placed at the edge of the canopy. Because young lychees are sensitive to wind and full sun, they benefit from fast-growing companions in their first years, for instance bananas or nitrogen-fixing shrubs, which shield them and supply mulch. As a slow, long-lived tree it is a plant of the later stages of succession, a goal of the planting rather than its pioneer.

In the Mediterranean climate

The lychee is no longer only a tropical crop. In the Axarquía region near Málaga, trials by the IHSM La Mayora showed that lychee and the related longan adapt well, and identified cultivars suited to commercial growing there. In Sicily, researchers from the universities of Palermo and Catania tested four cultivars over two seasons and found yields and fruit quality comparable to tropical growing areas; two cultivars showed alternate bearing, with a strong crop only every other year. In Israel lychee has been grown commercially for decades, and much of the research on its pollination by honeybees comes from there.

What makes the Mediterranean promising is the cool, dry winter that lychee needs for flowering. What makes it difficult is the dry, hot summer while the fruit is growing, calcareous soils, wind, and occasional frost on young trees. The lychee is not considered invasive in Europe and is not on the EU list of invasive alien species.

Propagation and care

Lychees are propagated mostly by air layering, sometimes by grafting. Seedlings vary and fruit late. Young trees need shelter from wind and frost, regular water and a permanent layer of mulch. Pruning after harvest keeps the crown low and encourages a uniform new flush.

How Terra Humana understands it

At Sa Medada the lychee is meant to test how far a tree of the subtropics can settle into a Mediterranean slope when it is surrounded by shelter, shade and living soil. As a slow, long-lived tree it belongs to the future canopy of the place, and its first task is simply to establish itself.