Cymbopogon citratus (Lemongrass)
Cymbopogon citratus (Lemongrass)
Contents
Introduction & History
Lemongrass is the aromatic grass that defines Southeast Asian cuisine — its bright, clean, citrus-ginger flavour is irreplaceable in Thai, Vietnamese, and Indonesian cooking. This tropical grass grows in dramatic, fountain-like clumps and fills warm gardens with a lemon scent so intense that merely brushing past it perfumes your hands for hours. In temperate climates, it has become one of the most popular summer container herbs.
History & Origin
Native to tropical South and Southeast Asia — India, Sri Lanka, Myanmar, and Malaysia. Cultivated for centuries across tropical Asia for cooking, traditional medicine, and essential oil production. The essential oil (citronellal and geraniol) is a major commercial product used in cosmetics, cleaning products, and insect repellents. It spread globally through colonial-era spice trade and is now grown in every tropical region.
Botanical Description
Dense, clump-forming tropical grass growing 90–150 cm tall and 60–90 cm wide. Leaves are long (60–100 cm), narrow (1–2 cm), sharp-edged, and blue-green, arching gracefully from the base. The culinary part is the fleshy, bulbous lower stem (the 'stalk'), which is pale green to white, layered like a leek. The entire plant is intensely lemon-scented. Rarely flowers in cultivation. No stolons — grows as a clump.
Stem: Semi-woody to woody at base • Height: 120 cm at maturity • Spread: 90 cm • Foliage: green • Flowers: green (rarely flowers) (rarely)
Planting & Cultivation
Plant divisions or nursery-grown clumps in spring after all frost danger, spacing 60–90 cm apart. Full sun in the warmest position available. Rich, well-drained soil. In cold climates, grow in large containers (30+ litres) that can be brought indoors before frost. Can also be started from fresh stalks bought at Asian grocery stores — root them in water first.
| Sun exposure | Full Sun |
| Soil pH | 5.0-8.0 |
| Spacing | 90 cm |
| Seed depth | 3–6 mm (surface-sow if light-dependent germinator) |
| Water needs | Moderate |
| Soil type | Well-drained, humus-rich loam; add perlite or grit for drainage |
Cultivation Details
Full sun, rich moist soil, and warmth — this is a tropical plant. Water freely during the growing season. Feed monthly with balanced fertiliser. In temperate climates, grow as an annual or overwinter indoors. The dramatic fountain habit makes it a striking architectural plant. In tropical climates, it grows year-round and can become a large, permanent clump.
Climate & Hardiness
Tropical — frost-sensitive below 0°C. Root-hardy to about −5°C in zones 9b–11 with heavy mulching (regrows from the base). In zones 8 and colder, treat as an annual or overwinter the root clump in a cool, dry place (lift, trim, and store like dahlias). Needs at least 4–5 months of warm weather (above 20°C) to produce usable stalks.
USDA zones: 9-11
Minimum temperature: 0°C
Seasonal Care
Spring: plant out after last frost; or restart from stored roots. Summer: peak growth — water and feed heavily. Autumn: harvest remaining stalks before frost; lift and store roots in cold zones. Winter: in zones 10–11, cut back old foliage; new growth resumes. In cold zones, store roots frost-free.
Propagation
By division of established clumps in spring — each division with several stalks and roots. Can also root fresh lemongrass stalks from grocery stores: place the bottom 5–8 cm (with root plate intact) in a glass of water; roots appear in 1–2 weeks. Pot up and grow on. Seed is rarely available and not the standard method.
| Method | Success rate | Time | Notes |
|---|---|---|---|
| Stem cuttings | 70–90% | 2—4 weeks | Softwood in spring, semi-ripe in summer; 8–12 cm |
| Division | 95%+ | Immediate | Split established clumps in spring or autumn |
| Seed | 50–80% | 14–28 days | Some require cold stratification; germination variable |
| Layering | 80–90% | 6–12 weeks | Pin low branch to soil; sever when rooted |
Diseases & Pests
Remarkably pest-free — the citrus oils deter most insects. Rust can occur in humid conditions. Spider mites on stressed or indoor plants. The strong scent actually repels many garden pests, making it a functional companion plant. No significant disease problems in the right conditions.
Culinary Uses
Indispensable in Southeast Asian cuisine. The lower stalk is bruised and added to Thai curries, soups (tom yum, tom kha), and stir-fries. Vietnamese cuisine uses it with chilli and fish sauce. Indonesian rendang and sate marinades rely on it. Also makes a superb herbal tea — steep sliced fresh stalks in hot water. Pairs with ginger, galangal, chilli, coconut milk, lime, and fish sauce. Always remove before serving or slice very finely.
| Category | Pairing suggestions |
|---|---|
| Baking | Shortbread, scones, cakes |
| Preserves | Jelly, syrup, sugar |
| Cocktails | Gin botanicals, spritzers |
| Honey | Infused honey, dessert garnish |
Medicinal & Aromatherapy
Rich in citral (the compound responsible for the lemon scent), which has anti-inflammatory, antifungal, and antimicrobial properties. Lemongrass tea is a popular digestive aid throughout Asia. The essential oil is used in aromatherapy for stress relief and as an insect repellent. Traditional Ayurvedic and Thai medicine uses it for fever, headaches, and infections.
| Compound | Properties |
|---|---|
| linalool | floral, calming |
| cineole | camphoraceous, expectorant |
| thymol | antiseptic, warm |
| carvacrol | pungent, antimicrobial |
| eugenol | clove-like, analgesic |
Container & Companion Growing
Container Growing
The standard method in cold climates. Use 30+ litre pots with rich potting mix. Full sun. Water daily in hot weather — lemongrass is thirsty. Feed fortnightly. The architectural fountain habit makes a dramatic container specimen. Bring indoors before first frost or lift and store the root clump dormant.
• Minimum pot size: 30–40 cm Ø, 15 L+
• Excellent drainage essential; add perlite
• Use free-draining potting compost with 20–30% perlite or grit
• Ensure drainage holes; stand on pot feet to prevent waterlogging
• Feed with dilute liquid fertiliser (half-strength) every 2–3 weeks in growing season
Companion Planting
The lemon scent repels mosquitoes, whiteflies, and some aphids. Plant near outdoor seating areas for pest deterrence. In tropical permaculture, grown as a hedge or border around vegetable gardens. The dense clumps suppress weeds. Good companion for ginger, turmeric, and other tropical herbs.
| ✓ Good companions | Roses, Brassicas, Fruit trees |
| ✗ Avoid planting with | Mint (invasive neighbour) |
Common Mistakes to Avoid
Not giving it enough heat — it needs sustained warmth to produce usable stalks. Over-harvesting from a small clump before it's established. Not using the right part (the outer leaves are too tough — it's the fleshy lower stalk that's culinary gold). Expecting it to survive frost without protection. Not watering enough — this is a thirsty tropical grass.
Harvesting & Preservation
Harvest outer stalks by pulling them away from the clump with a twisting motion, or cut at soil level. The usable portion is the lower 10–15 cm of the fleshy stalk. Peel tough outer layers to reach the tender core. Fresh stalks keep refrigerated for 2–3 weeks. Freeze whole stalks for long-term storage — they retain excellent flavour. Can be dried and ground, but fresh or frozen is vastly superior.
• Time of day: Early morning, after dew has evaporated but before intense midday heat volatilises essential oils
• Growth stage: Just before flowering, when essential oil concentration peaks. Once flowers open, the plant redirects energy from leaf production
• Season: Year-Round
• Part harvested: Stalks, Leaves
• Harvest rule: Never remove more than ⅓ of the plant at once; this ensures continued vigorous regrowth
• Technique: Cut stems cleanly above a leaf node with sharp scissors or secateurs. Tearing damages tissue and invites disease
| Method | Process | Shelf life | Best for |
|---|---|---|---|
| Air drying | Tie bundles, hang upside down in warm, dark, airy space | 6–12 months | Most herbs |
| Oven / dehydrator | Spread on trays, 35–45°C until crisp | 6–12 months | Fleshy-leaved herbs |
| Freezing (whole) | Blanch 5s, ice bath, pat dry, freeze flat on tray | 6 months | Basil, chives, parsley |
| Freezing (oil cubes) | Chop fine, pack into ice cube tray, cover with olive oil | 6 months | Any culinary herb |
| Herb salt | Layer herb and coarse salt 1:4, dry and grind | 12+ months | Rosemary, thyme, sage |
| Infused vinegar | Pack jar, cover with warm vinegar, steep 2–4 weeks | 6 months | Tarragon, dill, basil |
| Infused oil | Fill jar with dried herb, cover with oil, steep 4–6 weeks | 3–6 months | Rosemary, thyme, chilli |
Frequently Asked Questions
Can I grow lemongrass from a supermarket stalk?
Yes — buy fresh stalks with the root plate intact (bottom 1 cm). Place in a glass of water on a sunny windowsill. Roots appear in 1–2 weeks. Once well-rooted, pot up in rich compost and grow on in warmth.
Which part do I eat?
The lower 10–15 cm of the fleshy stalk, with the tough outer layers peeled away to expose the tender, pale core. The leaves are too tough to eat but make excellent lemongrass tea.
How do I overwinter lemongrass?
In zones 9b–11, mulch heavily and leave in the ground. In colder zones, lift the clump before frost, trim leaves to 15 cm, shake off soil, and store the root ball in a cool (5–10°C), dry place. Replant in spring.
Seasonal Care Calendar
🌱 Spring (Mar–May)
Water: Regular
Feeding: Regular feeding
☀️ Summer (Jun–Aug)
Water: Very Heavy
Feeding: Heavy feeding
🍂 Autumn (Sep–Nov)
Water: Regular
Feeding: Light feeding
❄️ Winter (Dec–Feb)
Water: Light
Feeding: No feeding
The essential Southeast Asian culinary grass — bright citrus-ginger stalks for Thai curries, tom yum, and Vietnamese dishes. Tropical (zones 9b–11, annual elsewhere). Dramatic fountain habit 90–150 cm tall. Grow from grocery store stalks. Repels mosquitoes. Container growing in cold climates.
Quick Reference: Cymbopogon citratus
Key Principles: Right location, well-drained soil, regular harvesting to promote growth, and appropriate winter protection for tender species.