How to Grow Lemon Grass
East Indian from Seed
The culinary lemon grass of Thai and South Asian cooking -- Cymbopogon flexuosus, the East Indian variety with the highest citral content and most complex flavour; a tender tropical grown as a UK pot herb in maximum warmth; surface sow at 20-25°C with patience for 21-40 day germination; outdoors in June only; harvest thickened stem bases by late summer; overwinter indoors frost-free; wear gloves when handling (sharp leaf edges)
Lemon Grass (Cymbopogon flexuosus, East Indian Lemon Grass) is the culinary grass of Thai, Vietnamese, Indonesian, and Indian cooking -- the citral-rich stalks that provide the characteristic lemon-fresh, slightly citrus-floral base note in curries, laksa, Tom Yum soup, satay marinades, and hundreds of other Asian dishes. In the UK, growing lemon grass from seed to harvested stalks is entirely achievable -- but it requires the one thing that a northern European climate cannot reliably provide: consistent warmth. This is a tropical grass from the coastal regions of India and Sri Lanka, and it grows only when warm, quickly slowing or stopping at temperatures below 15°C.
The East Indian variety (C. flexuosus, also known as Cochin Grass or Malabar Grass) is the variety preferred by professional chefs and food producers for its particularly high citral content and more complex flavour compared to the West Indian variety (C. citratus). In a warm UK summer, given a greenhouse, conservatory, or south-facing sheltered patio position, it grows into a graceful, arching clump of grass-like stems reaching 60-100cm, with a strong lemon-citrus fragrance from both the base stalks and the leaf blades. By late summer, the stem bases have thickened sufficiently for cooking -- the distinctive swollen, pale-purple-tinged lower portion that provides the culinary material.
Quick Facts at a Glance
Plant Type
Tender perennial (grown as half-hardy annual in UK) -- overwinter indoors for year-round
Harvest
Thickened stem bases (1-2cm diam.) for cooking; leaves for tea all season
Height
60-100cm; graceful arching grass stems; structural patio plant
Germination
Surface sow/light; 20-25°C; patient 21-40 days -- warmth is essential
Handle
Leaf edges sharp like paper -- wear gloves when pruning or harvesting
Difficulty
3 out of 5 -- needs consistent heat; patience with germination
Understanding the Plant
East Indian vs West Indian -- The Culinary Difference
There are two culinary Lemon Grass species: Cymbopogon flexuosus (East Indian, Malabar, Cochin) and Cymbopogon citratus (West Indian). Both produce edible lemon-fragrant stalks, but the East Indian variety has a higher citral content -- the compound responsible for the distinctive lemon-grass flavour -- and a more complex, slightly floral quality compared to the simpler lemon scent of the West Indian. East Indian is the variety grown commercially for essential oil production (Lemongrass oil) and is the preferred variety for serious culinary use. When recipes call for lemon grass, they typically mean the West Indian variety (which is more commonly sold as potted supermarket herbs), but East Indian provides a superior flavour for cooking.
The Warmth Requirement -- The Key to Success
Cymbopogon flexuosus is a tropical grass with a growing temperature range of approximately 18-35°C. Below 15°C growth effectively stops; below 5°C the plant is damaged or killed. In UK conditions, this means: germination must happen indoors with supplementary heat (20-25°C); the plants should not go outdoors until June when both air and soil temperatures are genuinely warm; they grow best in a greenhouse, conservatory, or sheltered south-facing patio position; and if overwintering is desired, plants must come back indoors before the first autumn frost. In a warm UK summer, lemon grass grows enthusiastically; in a cold, wet summer, growth is slow and stem development disappointing.
Leaf Edge Caution -- Wear Gloves When Handling
Lemon Grass leaves have very fine, sharp edges similar to paper cuts. The edges are imperceptible until they contact skin, at which point they leave thin but stinging cuts. Always wear gardening gloves when pruning, harvesting, or handling the stems. This is particularly important when harvesting the lower stalks, which involves bending or peeling back the outer leaf sheaths -- a process that can produce multiple small cuts if done bare-handed.
Sowing & Growing On
Surface Sow at 20-25°C -- Patience Required for 21-40 Day Germination
Surface sow onto free-draining moist compost without covering (light required). Maintain a consistent 20-25°C -- a heated propagator is ideal. Germination is slow and variable, typically 21-40 days. Do not conclude failure until 6 weeks have passed without germination. Consistent warmth is the critical factor.
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Surface sow indoors January-April at 20-25°C. Do not cover -- light required for germination. Use a heated propagator to maintain consistent warmth. Germination is slow and variable (21-40 days) -- patience is essential. Keep the compost consistently moist but not wet during the long germination period.
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Prick out into individual 10cm pots when seedlings are 5-8cm tall. Lemon Grass seedlings are delicate initially -- handle by the root ball rather than the stem. Use a free-draining, peat-free multipurpose compost with 20% perlite or grit. Keep consistently warm (minimum 18°C).
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Pot on into a large pot (25-30cm) as the plant grows. Grow on in maximum heat and sun. A greenhouse, conservatory, or sunny south-facing sheltered spot provides the conditions for vigorous growth. Do not move outdoors until June when temperatures are genuinely warm. Keep well watered and feed with a balanced liquid fertiliser fortnightly from June.
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Harvest thickened stem bases (1-2cm diameter) by late summer; leaves for tea at any time. For cooking, cut individual stalks at ground level when the base has reached 1-2cm diameter. The outer layers are tough -- peel back to the tender inner stalk for culinary use. Leaves can be snipped at any time and steeped in hot water for lemon grass tea.
Growing On & Care
In the Kitchen -- Culinary Uses
The swollen stalk base of Lemon Grass is the primary culinary material: it provides the distinctive citral-lemon background note to Thai green and red curries, Tom Yum soup, laksa, satay marinades, and seafood dishes throughout South and Southeast Asian cooking. To use: cut off the top two-thirds of the stalk (the grassy leaves are too tough to eat but can be used for tea and infusions), remove the outer tough layers, then finely slice, pound in a mortar, or freeze whole for later use. The slightly flattened, pale purple-tinged inner stalk is tender and aromatic. It can also be bruised and used whole in cooking (then removed before serving, like a bay leaf).
Maximising the UK Harvest
For the best lemon grass stalk development in a UK growing season: start early (January-February sowing) for the longest possible growing period; grow in a greenhouse or polytunnel for maximum heat accumulation; feed fortnightly with a balanced liquid fertiliser from June; water generously in hot weather; and harvest individual stalks progressively from August rather than waiting to harvest all at once. Each harvested stalk is replaced by new growth from the clump centre, so progressive harvesting continues to stimulate production.
Overwintering for Year-Round Production
Lemon Grass can be overwintered indoors in a frost-free location to provide year-round access to both the stalks and the leaves. Before the first autumn frost (typically October in most UK locations), bring the pot inside to a bright, frost-free room, conservatory, or heated greenhouse. Cut the plant back to 15-20cm to reduce water demands over winter. Water sparingly -- just enough to prevent the roots from drying completely. In spring, increase watering and move back into the warmest position available as temperatures rise. An overwintered plant resumes growth significantly faster than a freshly-sown seedling, producing harvestable stalks much earlier in the following season.
Lemon Grass Tea
The long grass-like leaves of Lemon Grass can be snipped and steeped in hot water at any time during the growing season to produce a fragrant lemon-ginger herbal tea. Use 4-6 leaves per cup, pour over water just off the boil, steep for 5-8 minutes, and strain. The flavour is lighter and more delicately floral than the stalks, with a sweet citrus quality and none of the slight fibrous texture of the cooked stalk material. Add fresh ginger, honey, or mint for a more complex infusion.
Companion Planting and Fragrance
Lemon Grass grown on a patio or terrace provides both the culinary resource and a fragrant structural element. The arching grass-like foliage creates a tropical, relaxed quality in any patio planting scheme. As a companion, the citral oils in the leaves and stems have some natural insect-deterrent properties -- traditionally lemon grass and lemon grass oil have been used to repel mosquitoes, and a pot of lemon grass near a patio seating area does provide some degree of deterrent effect, though not as effectively as concentrated essential oil products.
Frost Sensitivity
The single most important management point for UK Lemon Grass growing: the plant is killed by frost. Even a light frost that barely harms most other plants will damage or destroy Lemon Grass. Watch the weather forecast carefully in September and October and bring plants indoors well before the first frost is predicted -- do not wait until frost has actually occurred. A plant that has been frosted can sometimes recover if the frost was very light and brief, but prolonged or harder frost kills it outright.
Sowing & Harvest Calendar
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| Sow (Jan-Apr; indoor/heated) |
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| Outdoors/grow on warm (Jun-Sep) |
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| Leaf tea harvest (Jun-Oct) |
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| Stalk harvest (Aug-Oct) |
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| Overwinter indoors (Oct-May) |
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Common Problems & Solutions
| Problem | Likely Cause | What to Do |
|---|---|---|
| No germination after 3 weeks | Temperature inconsistent; seeds covered | Maintain a consistent 20-25°C throughout the germination period -- a heated propagator is essential. Surface sow without covering (light needed). Wait up to 6 weeks before concluding failure -- lemon grass germination is genuinely variable and slow. Do not sow in temperatures below 20°C. |
| Slow or stunted growth | Temperature too low; insufficient light | Lemon Grass effectively stops growing below 15°C. Grow in the warmest available position throughout the season -- greenhouse, conservatory, or sheltered south-facing patio. In a cold, cloudy UK summer, supplement with a grow light for indoor plants and provide maximum outdoor heat exposure when weather permits. |
| Stalks too thin for harvesting | Short growing season; cool summer | Start seeds in January-February for the maximum growing season. Feed fortnightly with a balanced liquid fertiliser from June. In a warm season, stalks reach 1-2cm diameter by late August; in a cool season they may not thicken sufficiently. Overwintering provides a head start the following season. |
| Leaf cuts on hands during harvest | Not wearing gloves | Always wear gardening gloves when handling lemon grass -- the leaf edges are fine and sharp enough to cause paper-cut-like injuries on contact with bare skin. The injury is minor but stinging and can be avoided entirely with gloves. |
Plant Specifications
The authentic citral-rich lemon grass of Thai cooking -- grown on your patio from summer to first frost
Surface sow at 20-25°C in a heated propagator from January-April. Be patient -- germination takes 21-40 days. Grow in maximum warmth throughout. Move outdoors in June only when genuinely warm. Feed fortnightly from June. Wear gloves when harvesting the thickened stalk bases. Bring indoors before first frost for year-round production. The East Indian variety provides the authentic high-citral flavour of Thai and South Asian cooking from your own garden.
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