Banana

What is a banana plant?

A banana plant looks like a palm or a small tree, yet it has no wood at all. It is a giant herb. The apparent trunk, the pseudostem, consists of leaf sheaths rolled tightly around one another; the true stem is a fleshy corm in the soil. From this corm come the roots, the leaves and, after some months, the flower stalk, which pushes up through the centre of the pseudostem and hangs out at the top as a heavy bunch.

Each pseudostem flowers only once. After the harvest it is cut down, and one of the side shoots from the corm, the suckers, grows on in its place. A banana clump therefore renews itself continually. It is less a single plant than a small colony from one root.

Origin and growth

Bananas come from the humid tropics of South-east Asia and New Guinea. Excavations at Kuk Swamp in the highlands of New Guinea point to banana cultivation several thousand years ago. Most of today's edible bananas are hybrids of two wild species, Musa acuminata and Musa balbisiana, many of them with three sets of chromosomes. They are sterile and form their fruit without fertilisation, which is why they carry no seeds and are propagated from suckers.

Under good conditions a banana flowers about 10 to 15 months after planting, and the bunch ripens 80 to 180 days later. In cooler climates both steps take longer.

Requirements

Warmth. Growth slows below 16 °C and stops at about 10 °C. Leaves can be damaged at 0 °C; below about -2 °C the plant may be killed to the ground, but the corm usually sprouts again.

Water. The large leaves evaporate a lot. The University of Florida recommends about 100 to 150 mm of water a month.

Soil. Deep, loose and well drained, rich in organic matter. Standing water damages the roots quickly.

Light and wind. Full sun or bright half shade. Wind shreds the leaves and topples stems carrying heavy bunches.

Fruit, use and harvest

A bunch is cut when the fruit is fully formed but still green; it ripens after cutting. The pseudostem that bore it is then removed. Beyond the fruit, the plant gives large leaves for wrapping and covering, and a great deal of soft, water-rich biomass. Banana sap stains clothing and is hard to wash out.

In the food forest

In a food forest the banana is a plant of the early years. It grows fast, shades young fruit trees and keeps the microclimate humid. In syntropic agriculture bananas are pruned and thinned regularly; the cut stems and leaves go straight onto the ground as mulch. Because the tissue is mostly water, it cools and moistens the soil as it rots. As the canopy of long-lived trees closes, the bananas give way. In permaculture they are also planted in rings around a compost or greywater pit, where nutrients and moisture collect.

In the Mediterranean climate

Bananas are grown commercially in several places around the Mediterranean and the nearby Atlantic. The Canary Islands harvest between 350,000 and 430,000 tonnes a season on about 9,000 hectares, mostly of the Cavendish type. In Israel most bananas have grown in net-covered screenhouses since the early 2000s; the nets keep off the wind, and yields have risen by about 30 percent. On Crete's south-east coast they grow outdoors as well as under plastic. On a plantation near Orosei, about two hours north of Sa Medada, bananas have been bearing fruit for years.

The limits are cold and drought. In a cool winter the plants stand still, and a bunch that forms late in the year needs many more months to ripen. A dry summer without irrigation cuts growth sharply. Sheltered, warm spots near walls or slopes facing the sun, wind protection and permanent mulch make the difference. Edible bananas are sterile and cannot spread by seed; the genus is not on the EU list of invasive alien species.

Propagation and care

Bananas are propagated from suckers. Large sword suckers with narrow leaves and a strong base are preferred; broad-leaved water suckers grow weakly. One mother stem with one or two followers of different ages keeps a clump productive. Dead leaves and old stems are cut and left as mulch.

How Terra Humana understands it

At Sa Medada the banana is meant to show how quickly shade, moisture and soft biomass can be created on dry ground. Each harvested stem returns to the soil. Whether and how the bananas fruit on the slope is something we watch closely; their first task is to help the slower trees around them through their early summers.