Cymbopogon citratus is an aromatic, evergreen, densely clump-forming, perennial grass producing numerous stiff stems arising from a short rhizomatous rootstock, and growing around 1.5 metres tall.

Lemon grass is a pleasantly aromatic plant that is widely cultivated in the tropics, both on a commercial scale and in gardens, and especially in southeast Asia. It is used as a food flavouring, especially for Asian cuisine; as a medicinal herb; the source of an essential oil; and as a soil improver and stabilizer. It is also an excellent restorer of worn out soils and is grown as an ornamental in gardens, where it can be used to form a small hedge.

Known Hazards

None known

Habitat

Not known in a wild situation.

Cultivation Status

Cultivated, Ornamental

Cultivation Details

Cymbopogon citratus is a plant of the tropics and subtropics, where it can be found at elevations up to 1,400 metre, though it grows best below 500 metres.
It grows best in areas where annual daytime temperatures are within the range 24 - 30°c, but can tolerate 18 - 34°c.
It can be killed by temperatures of 10°c or lower.
It prefers a mean annual rainfall in the range 1,500 - 3,000mm, but tolerates 700 - 4,200mm.

Prefers a moisture-retentive soil in full sun.
Requires a well-drained soil - commercial plantations often favour sandy soils, although good growth has also been observed in Australia on a clay soil with pH 9.6 and in Sarawak on an acid peat soil. Prefers a pH in the range 5 - 5.8, tolerating 4.3 - 7.3.
The plant tillers strongly and the number of tillers is directly correlated with the number of leaves and with oil yield. Only young, expanding leaves synthesize and accumulate essential oil.
Harvesting begins when the crop is 120 - 240 days old, and the plant is subsequently harvested every 90 - 120 days.
The plant has an economical life of 4 - 6 years.
The average annual foliage yield is 30 - 50 tonnes per hectare, yielding 75 - 250 kg lemongrass oil (0.25 - 0.50%).
Foliage yield of 100 tonnes per hectare has been achieved under optimum circumstances, and with efficient management and improved selections the oil yield can be increased to 0.4 - 0.6%.
Harvesting the top parts gives an oil yield of 0.6%, while the lower parts yield only 0.15%.
Fresh grass yields 0.2 - 0.4% oil, with an average yield of 50 - 120 kilos of oil/ha per annum. Yield of foliage is higher on fertile heavy soils, but under these conditions the oil usually has a lower citral content.
The plant seldom flowers.
Lemongrass should be stored separately from other foods, or should be well wrapped, otherwise its strong scent will taint the other foods.

Edible Uses

The heart of the young shoots is eaten as a vegetable with rice.
The basal portions of the leafy shoots have a delicious lemon-like aroma and are used as a flavouring in soups, sauces and curries.
Particularly popular in southeast Asia, they are added to spicy sauces such as 'sambal goreng' and 'sambal petis' and to cooked fish and fish sauces.
Older leaves can be cooked with other foods in order to impart their lemon-like flavour. They are removed before serving.
A refreshing tea can be brewed from the leaves.
It can be served hot or cold.
It can be sweetened with sugar.

The essential oil is used as a flavouring in the food industry in soft drinks and various food.

Medicinal

Lemon grass is a bitter, aromatic, cooling herb that increases perspiration and relieves spasms.
The essential oil obtained from the plant is an effective antifungal and antibacterial.
The essential oil contains about 70% citral, plus citronellal - both of these are markedly sedative.
Internally, the plant is used principally as a tea in the treatment of digestive problems, where it relaxes the muscles of the stomach and gut, relieving cramping pains and flatulence.
It is particularly useful for children, for whom it is also used to treat minor feverish illnesses.

Externally, especially in the form of the extracted essential oil, the plant is a very effective treatment for a range of skin conditions including athlete's foot, ringworm, lice and scabies.
It is also applied to ease the pain of arthritic joints.

Agroforestry Uses

A good soil conditioner in worn out land. The plants quickly produce a bulk of organic material which soon rots down, attracting worms and other beneficial creatures and quickly enriching the soil.
A row of lemongrass plants can be used as a divider in the garden - it can help to contain more invasive plants such as sweet potato, and also as a barrier to prevent weeds growing into the garden.
The grass is useful for soil improvement and erosion control.

Other Uses

An essential oil obtained from the plant is used in perfumery, scenting soaps, hair oils, cosmetics and as an insect repellent.
The oil consistis mainly of citral and is an important starting material in the perfumery industry for the production of 'ALPHA'- and 'BETA'-ionones, which in low concentrations have the odour of violets.
It is also used in the synthesis of vitamin A.
The essential oil obtained from the leaves has been shown to be an effective fungicide in treating pathogenic fungi on the cultivated plant Jatropha curcas.
The fresh leaves, crushed in water, are used as a hair wash and toilet water.
The plant is used for cellulose and paper production.

Propagation

Seed - not often produced.
Division of established clumps. This is best done annually or they can become too crowded and suffer, commercially the plant is divided every 4 - 6 years. The size of offshoots used depends on local preference; larger shoots normally root quicker and grow faster. The offshoots are cut back to 10 - 15 cm, trimmed of dead and excess roots and then planted either direct or into nursery beds.