How to Plant and Grow Lemongrass

Lemongrass is a tropical plant native to southeast Asia. It is prized for its intense citrus-like scent and flavor and doubles as an ornamental grass with vibrant green foliage and strappy texture. In addition to being used in cooking and for herbal tea, lemongrass also serves as an insect-repellent. In warm climates, it is grown in the garden year-round. Below Zone 9, it is either grown as an annual or planted in containers and overwintered indoors.

Where to Plant Lemongrass

Lemongrass needs full sun and moist, well-drained soil that can be slightly acidic, neutral, or slightly alkaline.

While lemongrass is not particularly colorful, it can serve as a wonderful companion plant. With its vibrant green leaves and grassy texture, it adds interest to a garden and helps break up coarse foliage. In an herb garden setting, use the tall grass as a focal point among lower-growing herbs. Beyond its use as a culinary plant, it can be planted as a fast-growing ornamental grass in garden beds or containers.

How and When to Plant Lemongrass

Lemongrass is a heat-loving plant. You can plant it in the garden when there is no longer any danger of spring frost. Dig a hole that is about 1.5 as wide as the root ball and about as deep. Set the plant in the hole and backfill it with original soil.

Space the plants 24 inches apart. If you grow lemongrass as an annual, plant it closer together, about 18 inches apart.

Lemongrass Care Tips

Lemongrass is an undemanding plant and easy to grow.

Light

Plant lemongrass in full sun, which will encourage a more intense flavor as well as a fuller, more lush plant. In part shade, plants have a much looser growth habit and tend to become floppy.

Soil and Water

Lemongrass grows best in well-drained soils with a pH between 5.5 and 7.5. Heavy or clay soil is not suitable.

Established plants can tolerate a dry spell but for lush growth, they need consistent and even moisture. Water the plant regularly and deeply in the absence of rain.

Temperature and Humidity

Lemongrass is a tender perennial that grows best in warm weather and won’t do well in temperatures below 60 degrees F. It does not survive winters below zone 9. In a cold climate, you can either grow it in a container and overwinter it indoors or grow it as an annual.

Lemongrass does fine in hot and humid weather, in fact, it does best in humid growing conditions that mimic its native habitat in southeast Asia.

Fertilizer

Like all grasses, lemongrass requires nitrogen to grow. During the growing season, give it a fertilizer that is high in nitrogen. For in-ground plants, use a slow-release granular fertilizer about once a month. Potted lemongrass needs more frequent fertilization as the nutrients wash out rapidly. Use a liquid high-nitrogen fertilizer or fish emulsion about every two weeks.

Pruning

Other than removing the dead foliage, lemongrass does not need much pruning during the growing season. If you grow it as a perennial outdoors, leave the foliage standing during the winter, as this protects the plants from frost. In late winter or early spring, just before the new growth starts, cut the foliage back to 6 inches. Potted plants that overwinter indoors can be cut back any time during the winter.

Potting and Repotting Lemongrass

Plant lemongrass in a container that is at least 12 inches in diameter and has large drainage holes. A large container, especially one made of heavy material (glazed ceramic or terra-cotta) is less likely to topple over.

Use well-draining potting mix and keep in mind that container plants need more frequent watering and fertilizer than in-ground plants.

Repot the plant with fresh potting mix every spring even if the roots have not outgrown the container yet, as the plant will do better in a replenished growing medium.

Pests and Problems

With the exception of rust, lemongrass does not have serious pest or disease problems. The rust is caused by a fungus that manifests itself through yellow spots and brown elongated streaks on the leaves as well as dark brown pustules on the underside of the leaves. Rust can kill the plant. If you detect it, prune the diseased foliage and discard it. Keep the plant healthy with regular fertilization and adequate moisture. Watering it at the base instead of overhead can help prevent the fungus.

How to Propagate Lemongrass

Like all grasses, lemongrass can be propagated by digging up the clump and dividing it. You can even start a new plant by rooting a shoot from the grocery store as long as it's fresh. Trim off the top few inches and place the shoot in a cup of water. Change the water daily. After a few weeks, roots begin to grow. Plant the lemongrass in well-drained potting soil.

Lemongrass can also fairly easily be grown from seed indoors. Fill small pots with damp potting mix and place the seeds on the soil surface. Press them down lightly but do not cover them as they need light to germinate. Cover the pots with a plastic dome. The temperature should be at least 68 degrees F. Bottom heat from a seedling heating mat helps with germination. Keep the seeds moist but not soggy. Germination takes 7 to 14 days.

Harvesting

Throughout the growing season, you can gather leaves as needed by cutting them at the base of the plant. To harvest whole stalks of lemongrass, cut the stalks when they're roughly 2-1/2 inches long and nearly an inch wide at the base.

Lemongrass requires liquid to disperse its essential oils. The simplest way to do this is to steep the leaves in hot water for a refreshing tea, or use it to season soups, stews, and marinades. You can also chop any excess stalks and freeze them for up to one year, and leaf pieces for up to five months.

You can also preserve leaves by hanging them upside down in a dark place to dry. Once the stalks are dry, chop them and store in an airtight container to be used at a later time. The dried leaves make a great addition to green tea. Just remember: Drying herbs concentrates their flavor, so for teas and other recipes, you need less dry lemongrass than fresh lemongrass.

Types of Lemongrass

West Indian Lemongrass

Cymbopogon citratus has strap-shaped light green leaves and thick stalks, which makes it the preferred lemongrass for culinary use.

East Indian Lemongrass

Cymbopogon flexuosus, also called Malabar grass, has stalks with purple tinges. The stalks are thinner and taller than the stalks of West Indian lemongrass. It is a vigorous grower and often favored by gardeners because it is resistant to rust.