There are two species of the genus Cymbopogon which are known as lemongrass. Cymbopogon citratus is also referred to as "West Indian Lemongrass", while C. flexuosus is variously known as "East Indian Lemongrass", "Malabar Grass" or "Cochin Grass". They can be utilised interchangeably, but C. citratus is generally preferred for culinary use, and C. flexuosus for oil extraction. Citronella Grass, Cymbopogon nardus is closely related, and can also be used in cooking, although its main use is in the production of insect repellants.
All three are vigorous clump forming tropical grasses which rapidly make large plants up to 2m tall under suitable conditions. They will not stand frost, but can be cultivated in the UK either as annuals, or by cutting off most of the leaf and keeping the base of the plant frost free and fairly dry over winter. Besides their culinary potential, these plants all repel biting insect pests such as mosquitoes and stable flies as well as plant pests such as whitefly. Conversely, lemongrass oil is sometimes used as a lure to attract bees.
This species rarely sets seed, and I have been unable to source any in the UK. It must, therefore, be propagated vegitatively, either by division, or from the bases of fresh lemongrass stems bough from a grocery.
Unlike the former species, the East Indian lemongrass sets seed readily and seed my be obtained from all the major retail seed companies in the UK. The seed germinates in about 5 to 7 days at temperatures of 20° to 25° Celsius, but germination rate is unlikely to be more than 50%.
Plants grow rapidly in warm weather, needing copious amounts of water and generous feed. The disadvantage of this species relative to C. citratus seems to be that it multiplies too rapidly, producing a large clump of fairly thin stems.
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