Lemon Grass

About Lemon Grass

Lemon grass is a tender, aromatic perennial grass native to tropical Asia, forming dense clumps of slender, grey-green leaves with a distinctive citrus fragrance. In the UK, it's grown primarily as a culinary herb for Southeast Asian cooking, valued for its fresh lemon flavour in curries, soups, and teas. The plant produces tall, graceful foliage that can reach over a metre in height during the British summer. UK gardeners typically cultivate lemon grass in containers that can be moved indoors during winter, as it cannot survive frost.

UK fact: Lemon grass has become increasingly popular in British gardens since the 1990s alongside the rise of Thai and Vietnamese cuisine, with many UK gardeners now growing it on sunny patios and in conservatories to harvest fresh stems year-round.

Watering Lemon Grass

Keep the soil consistently moist during the growing season from late spring through summer, watering two to three times weekly in warm weather as lemon grass is naturally adapted to tropical monsoon conditions. In containers, check the compost daily during hot spells as pots can dry out rapidly. Reduce watering significantly in winter when growth slows, allowing the top few centimetres of compost to dry between waterings. Avoid waterlogging, which can cause root rot, but never let the plant become completely dry.

Sunlight requirements

Lemon grass requires full sun to thrive, needing at least six hours of direct sunlight daily to develop its characteristic citrus oils and flavour. In the UK, position containers in the sunniest spot available, ideally a south-facing patio or against a warm wall. During summer, plants benefit from being outdoors in maximum light, but must be brought inside before the first autumn frosts.

Soil and feeding

Lemon grass thrives in rich, moisture-retentive compost that drains freely, making a peat-free multipurpose compost mixed with additional perlite or horticultural grit ideal for container cultivation. The plant prefers a slightly acidic to neutral pH between 6.0 and 7.0. In the rare instances where it's grown in the ground during summer (in very sheltered locations), incorporate plenty of organic matter to improve both drainage and moisture retention. Good drainage is essential to prevent root rot, particularly during the cooler British months.

Feed container-grown lemon grass fortnightly from May through September with a balanced liquid fertiliser to support vigorous leaf growth. Alternatively, incorporate a slow-release fertiliser into the compost in spring and top-dress with well-rotted compost mid-summer. Reduce feeding to monthly or cease entirely in winter when the plant is semi-dormant.

Pruning Lemon Grass

Remove any dead, damaged, or yellowing outer leaves throughout the growing season to maintain plant health and appearance. In late autumn before bringing plants indoors, cut back the foliage by about half to reduce the plant's size and make overwintering more manageable. Harvest stems by cutting them at ground level, selecting the thickest, most mature stalks from the outer edges of the clump. Regular harvesting encourages fresh growth and prevents the clump from becoming congested.

Propagating Lemon Grass

Lemon grass is most easily propagated by division in late spring when the plant is actively growing. Carefully remove the plant from its pot, tease apart the clump into sections with roots attached, and pot up individual divisions into fresh compost. Alternatively, root fresh lemon grass stems purchased from supermarkets by placing the base in water until roots develop (usually 2-3 weeks), then potting up. Division is preferable to seed, which is rarely available in the UK and slow to germinate.

Common problems

Lemon grass is relatively trouble-free in the UK, with most problems arising from cultural conditions rather than pests or diseases. Overwatering or poor drainage can lead to root rot, particularly in winter, causing yellowing leaves and plant collapse. Red spider mite may occasionally infest plants kept in hot, dry conditions indoors, causing fine webbing and stippled foliage; increase humidity and consider biological controls. Brown leaf tips typically indicate underwatering, low humidity, or cold damage, whilst failure to thrive is usually due to insufficient light or temperatures below 10°C.

Spot a problem with your plant? Photograph the affected area using the Loam app and it will suggest the most likely cause and treatment.

Safety

Humans

Safe

Cats

Safe

Dogs

Safe

Toxicity information is for general guidance only.

Seasonal care calendar

Monthly care guide for Lemon Grass in the UK, based on average conditions.

Frequently asked questions

Can you grow lemon grass outdoors in the UK?

Lemon grass can be grown outdoors in the UK during summer (May to September) in a sunny, sheltered position, but it must be brought indoors before the first autumn frost as it cannot survive British winters. Container cultivation is essential for easy movement between outdoors and a frost-free location such as a conservatory, heated greenhouse, or bright windowsill where temperatures remain above 10°C.

Why is my lemon grass turning brown and how can I save it?

Brown leaf tips usually indicate underwatering, low humidity, or cold damage, whilst entire brown leaves suggest more serious stress from frost exposure or root rot. The Loam app can help you diagnose the specific cause based on your care routine and set watering reminders tailored to your conditions. Trim away brown foliage, adjust watering, ensure adequate warmth, and the plant should recover if the roots remain healthy.

How do you harvest lemon grass without killing the plant?

Harvest lemon grass by selecting the thickest, most mature stems from the outer edges of the clump and cutting them at ground level with a sharp knife. Take no more than one-third of the stems at a time to allow the plant to continue growing vigorously. The lower white and pale green portions are most flavourful for cooking, whilst regular harvesting encourages fresh growth and prevents overcrowding.

Related plants

• Basil
• Lemon Verbena
• Lemon Balm