Moringa

What is moringa?

Moringa looks fragile at first sight: a slender trunk with pale, corky bark, a light crown of finely divided leaves, and long, three-sided pods hanging like drumsticks. Yet it is one of the fastest-growing trees of the dry tropics. Its young leaves are cooked as a vegetable or dried, its green pods go into curries, and its seeds give an oil that does not easily turn rancid.

Origin and growth

Moringa oleifera comes from the foothills of the Himalaya in north-western India. From there it spread across South Asia and on to Africa, and today it is grown throughout the tropics and subtropics. It usually reaches 10 to 12 metres. Left uncut it can grow three to five metres in a year, according to ECHO. It takes cutting well: pruned or pollarded, it sprouts vigorously and forms a bushy crown.

Requirements

Cold. A light frost does little harm, a freeze kills the tree back to the ground; established roots usually resprout. In cool weather it sheds its leaves and rests.

Water. Moringa tolerates drought thanks to a deep taproot, but under constant water stress it produces much less foliage. Waterlogging harms it.

Soil. Well drained, from sandy to loamy; it copes with poor soils.

Light. Full sun and heat.

Leaves, pods and harvest

Leaves can be picked through the growing season. In intensive leaf plantings, trees are kept low and cut every 35 to 45 days, with water and fertiliser. Pods are harvested young and tender for cooking, or left to ripen for their seeds. The seeds give ben oil; the press cake contains the protein that clarifies cloudy water. The root and root bark are not eaten.

Constituents and effects

Moringa leaves are a nutrient-rich vegetable. Leaves grown on Tenerife were notably rich in calcium, potassium and iron. In Ayurveda, where the tree is called shigru, and in the folk medicine of many tropical countries, almost every part of the plant has a tradition of use.

The scientific evidence for medical effects is weaker than its popularity suggests. In a 2021 meta-analysis of seven small trials with 257 participants, not all of them randomised and lasting 28 to 90 days, fasting and post-meal blood sugar decreased and HDL cholesterol rose slightly, while HbA1c, LDL, total cholesterol and triglycerides showed no significant change; the blood sugar results varied greatly between studies, and the authors consider long-term benefit and safety still open. A 2020 systematic review on blood sugar found 33 animal studies but only eight human studies. Much of the research on anti-inflammatory and antioxidant effects comes from animals and cell cultures. Leaves and seeds are generally well tolerated in normal amounts; rare allergic reactions have been reported. Root and bark contain alkaloids such as spirochin and are considered unsafe to eat.

In the food forest

Moringa is a pioneer and a biomass tree. It grows fast enough to give young, slower trees light shade within a season, and its fine leaves let much light through. In syntropic agriculture it is cut back regularly; the branches and leaves go to the ground as mulch and decompose quickly. Unlike many pioneer trees, moringa is not a legume and does not fix nitrogen, so it combines well with nitrogen-fixing plants such as leucaena. In the long run it gives way to taller trees or is kept as a low, regularly cut hedge.

In the Mediterranean climate

In Spain moringa is grown on the subtropical Mediterranean coast and in the Canary Islands. Researchers who analysed leaves from Tenerife found high mineral levels and count the island among the best-suited places to grow it. On a plantation near Orosei, about two hours north of Sa Medada, moringa has been bearing for years. Its heat and drought tolerance suit the Mediterranean summer; the limiting factor is winter cold, which costs leaves and, in a hard frost, the whole top.

In northern Australia moringa has escaped from gardens and naturalised in places; a Queensland assessment rates it a minor weed that spreads slowly into thickets around parent trees. In Hawaii it is naturalised on O'ahu but considered low-risk. It is not on the EU list of invasive alien species.

Propagation and care

Moringa grows easily from seed and from thick cuttings. Young trees are cut back early to encourage branching. In frost-prone places a deep mulch over the root collar helps the plant to resprout after a cold winter.

How Terra Humana understands it

At Sa Medada moringa is meant to show how quickly a heat-hardy pioneer can bring shade, leaves and biomass to dry ground. Each cut returns to the soil. Whether it remains a tree, a hedge or a passing helper of the slower trees is something the place itself will show.