Common Name: Lemon Grass

General Information

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 ou soils and is grown as an ornamental in gardens, where it can be used to form a small hedge.

Known Hazards

None known

Botanical References

Range

A tropical plant, not known in the wild, but probably originating in Sri Lanka or Malaysia.

Habitat

Not known in a wild situation.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Perennial
Height	1.50 m
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[310. 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 foods[, ].

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[]..

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