Lemongrass (Cymbopogon citratus) is a tropical perennial grass prized for its intense citrus fragrance and flavour. Forming tall, dense clumps of slender, arching green leaves, it can reach up to 1.5–2 metres in height and spread to about 1 metre wide, making it both a productive culinary plant and an attractive garden specimen.

The edible portion is the tender, pale inner stalk at the base of each stem, which is used extensively in Asian cuisine — particularly in soups, curries, stir-fries, and marinades. The outer leaves, though too tough to eat, are excellent for infusing flavour into broths and teas.

Beyond the kitchen, lemongrass is valued in traditional herbal medicine for its anti-inflammatory and antioxidant compounds. Its essential oil is widely used in aromatherapy, and the plant's strong lemony scent has natural insect-repelling properties, making it a useful companion in the herb or vegetable garden.

Lemongrass thrives in warm, sunny conditions with well-drained soil and consistent moisture. In frost-prone climates, it is best grown in containers that can be brought indoors during winter. Given the right conditions, this versatile and vigorous herb will reward gardeners with abundant harvests throughout the warm growing months.

How To Grow

How to Grow Lemongrass

Starting Your Plants

Lemongrass can be started in three ways:

• From seed: Sow seeds indoors 6–8 weeks before the last expected frost, pressing them lightly into a moist seed-starting mix. Keep at 21–24°C. Germination typically takes 2–3 weeks.
• From purchased plants: These can be transplanted directly into the garden or a large container once warm weather is reliably established.
• From fresh stalks: Place the trimmed base of a fresh stalk in a glass of water. Once roots reach about 2–3 cm, pot up into soil.

Site Selection

Choose a position in full sun — lemongrass needs at least 6–8 hours of direct sunlight daily. Soil should be fertile, rich in organic matter, and free-draining. In containers, use a quality potting mix and ensure drainage holes are unobstructed.

Planting

Space plants 60 cm apart, with 90 cm between rows to allow for their mature clump size. Plant so the root ball sits just below the soil surface. In cool climates, grow in large containers (at least 30 cm diameter) so they can be moved indoors before temperatures approach 0°C.

Ongoing Care

• Watering: Keep the soil consistently moist, particularly in hot weather. Avoid waterlogging.
• Feeding: Apply a balanced liquid fertiliser every 2–3 weeks during active growth to support vigorous clump development.
• Mulching: A layer of organic mulch around the base retains moisture and moderates soil temperature.
• Overwintering: In frost-prone climates, cut plants back to about 15 cm, pot up if not already containerised, and overwinter in a warm, bright spot indoors.
• Division: Every 2–3 years in spring, divide established clumps to rejuvenate growth and propagate new plants.

Harvesting

Harvesting Lemongrass

When to Harvest

Lemongrass is ready to harvest when individual stalks are at least 30 cm tall and approximately 1–1.5 cm thick at the base. This typically occurs around 4–6 months after planting from seed, or sooner if growing from divisions or purchased plants. Well-established clumps can be harvested multiple times throughout the warm growing season.

How to Harvest

1. Select mature stalks — choose outer stalks that are firm, plump, and pale green to white at the base. Leave younger, thinner inner stalks to continue growing.
2. Cut or snap at the base — using a sharp knife, cut the stalk as close to the ground as possible, or firmly snap and twist it free. Cutting low encourages vigorous regrowth from the base.
3. Trim the stalk — remove the tough, fibrous outer leaves and the green upper portion. The usable part is the white to pale-yellow inner core at the base, typically the lowest 10–15 cm.

Storing Your Harvest

• Refrigerator: Wrap trimmed stalks in a damp cloth or paper and store in a sealed bag for up to 2–3 weeks.
• Freezer: Lemongrass freezes exceptionally well. Freeze whole trimmed stalks, or finely slice and freeze in ice cube trays topped up with water for convenient portioning.
• Dried: The leaves can be dried and used for herbal teas, though the flavour is milder than fresh stalks.

Encouraging Regrowth

Regular harvesting stimulates the plant to produce new stalks. Avoid removing more than one-third of the clump at any one time to maintain the plant's vigour and ensure continued productivity.

Common Problems

Common Problems with Lemongrass

Pests

Aphids can cluster on young stems and leaves, sucking sap and causing distorted growth. Blast them off with a strong jet of water or apply insecticidal soap.

Spider mites thrive in hot, dry conditions, causing stippled, yellowing leaves. Increase humidity around the plant and treat with a neem oil solution.

Grasshoppers and caterpillars may chew through the foliage. Hand-pick caterpillars where possible and use appropriate organic controls if infestations are severe.

Diseases

Root rot is the most common disease, caused by overwatering or poorly drained soil. Ensure the planting site or container drains freely and avoid waterlogging.

Rust (a fungal disease) can appear as orange-brown pustules on leaves, especially in humid conditions with poor airflow. Remove affected leaves and improve spacing between plants.

Leaf blight caused by fungal pathogens can produce brown, water-soaked lesions. Avoid overhead watering and remove infected material promptly.

Other Issues

• Yellowing leaves often indicate overwatering, poor drainage, or nutrient deficiency — particularly nitrogen. Apply a balanced fertiliser during the growing season.
• Poor growth or die-back in cooler months is normal for this tropical plant. In colder climates, bring container-grown plants indoors before temperatures drop near 0°C.
• Overcrowding reduces vigour over time. Divide large clumps every 2–3 years in spring to rejuvenate growth.