Lemongrass is a tropical grass whose pale lower stalks give a clean, lemony perfume to Thai, Vietnamese, Malaysian and Indonesian curry pastes, soups and marinades.
What it is¶
Lemongrass is a tall, clump-forming tropical grass. The part used in cooking is the pale, tightly layered lower stalk, which looks like a woody spring onion and carries a concentrated lemon scent without any of the sourness of actual lemons.
The culinary species is mostly Cymbopogon citratus, often called West Indian lemongrass although it is Asian in origin. Cymbopogon flexuosus, East Indian or Cochin lemongrass, is grown mainly for its essential oil. Closely related species give citronella oil (C. nardus and C. winterianus) and palmarosa oil (C. martinii); none of those is used as a food herb.
The lemon aroma is almost entirely down to citral, a mixture of two aldehydes (geranial and neral) that is also present in lemon peel, lemon verbena and lemon balm.
Origins and history¶
Lemongrass has been cultivated in South and Southeast Asia for a very long time, and its precise wild origin is uncertain; C. citratus is known mainly as a cultivated plant. It spread with trade and migration around the tropics, reaching the Caribbean, Latin America and Africa, and it was being distilled for oil in India by the 19th century.
In the kitchen it is most closely associated with the cooking of mainland and maritime Southeast Asia: thai cuisine, vietnamese cuisine, Lao and Khmer cooking, and the spice pastes (bumbu and rempah) of indonesian and malaysian cuisine. Sri Lankan cooks use it too, and in much of the Caribbean, West Africa and Latin America it is best known as "fever grass", brewed as a tea.
Flavour and aroma¶
Fresh lemongrass smells of lemon sherbet and lemon zest, with floral and slightly gingery notes and a grassy freshness. It has no real sourness and little bitterness. The flavour is most concentrated in the bottom 10–15 cm of the stalk; the upper green leaves are fibrous and weaker but still aromatic enough for stock and tea.
Dried lemongrass keeps a recognisable but flatter, hay-like lemon note. Frozen stalks are much closer to fresh.
In the kitchen¶
Lemongrass is fibrous, so there are two approaches: bruise and remove, or chop so finely it disappears.
Preparing a stalk. Cut off the root end and the top two-thirds of the stalk. Peel away the one or two dry outer layers until you reach the pale, tender core. That core is what goes into pastes and salads.
- Soups and broths. For tom yum and tom kha gai, cut the stalks into 5 cm lengths and bash them with the back of a knife or a pestle to split the fibres. Simmer for 10–15 minutes and leave them in the bowl (they are not eaten). Two stalks per litre of broth is a sensible starting point.
- Curry pastes. Lemongrass is a core ingredient of thai green curry paste and thai red curry paste. Slice the tender core very thinly across the grain before pounding; a pestle and mortar handles it better than most blenders.
- Stir-fries and marinades. Vietnamese bò xào sả ớt (beef with lemongrass and chilli) and grilled lemongrass pork use finely minced lemongrass, fried until fragrant.
- Skewers. Trimmed whole stalks make aromatic skewers for minced chicken, prawn or pork.
- Drinks and sweets. Infuse bruised stalks in sugar syrup, custard or coconut milk, or steep the leaves in hot water for tea.
💡 Slice across the grain
If lemongrass is going to be eaten rather than fished out, slice it as thinly as possible across the stalk before chopping further. Cutting along the fibres leaves chewy threads, however fine you think you have minced it.
Buying and storing¶
Choose firm, heavy stalks with tight layers and no wrinkling or dry, grey bases. Wrapped loosely in the fridge, fresh stalks keep for one to two weeks.
Lemongrass freezes very well: trim, wrap tightly and freeze whole for up to six months, or freeze the prepared, sliced core ready for pastes. Jars of lemongrass paste are convenient but usually contain oil, salt and acid; tubes are better than nothing. Dried and powdered lemongrass are best kept for tea and dry rubs. See freezing herbs.
Substitutes¶
No substitute is perfect. The finely grated zest of one lemon plus a small slice of ginger approximates one stalk in a curry or soup. A torn makrut lime leaf or two adds a different but complementary citrus note. Lemon verbena and lemon balm share the same citral aroma and work in infusions and desserts, though not in pastes.
Pairs well with¶
Galangal, ginger, garlic, shallots, chillies, makrut lime leaves, coriander leaf, thai basil, turmeric, coconut milk, fish sauce, lime, prawns, chicken, pork and beef.
Growing your own¶
Lemongrass is easy to grow from a supermarket stalk. Choose fresh stalks with the base intact, stand them in 2–3 cm of water on a sunny windowsill and change the water every couple of days. Roots appear in one to three weeks; once they are 2–3 cm long, pot up in a free-draining compost.
It is a tropical grass and not frost-hardy. In Britain, grow it in a pot outdoors from June to September in a warm, sunny spot, water freely and feed monthly, then bring it indoors before night temperatures fall below about 10°C. Over winter it needs a bright spot and very little water. Divide congested clumps in spring.
Harvest by cutting stalks at soil level once they are at least 1 cm thick. The leaves have sharp edges, so wear gloves when handling a mature clump. See growing herbs indoors and propagating herbs.