How to Grow Lemongrass

One of the most useful herbs, learning how to grow lemongrass can also add visual interest to your garden. Its long leaves sway gently in the summer breeze filling your outdoor space with color, interest and movement.

As summer turns to fall the leaves turn from light green to pleasing shades of red or burgundy providing further colorful internest.

In addition to being visually attractive you can also use the plant to add flavor to your home cooked meals, in aromatherapy or as an essential oil.

One of the main attractions of learning how to grow lemongrass is that this attractive, fast growing plant is also a great companion plant, boosting other plants in your garden and deterring pests such as mosquitos.

If you want to learn more about this useful, attractive herb, including how to grow the plant, this guide is full of the information that you need.

Learn how to grow this useful herb.  

Warning, lemongrass contains oils such as cyanogenic glycosides. This means that the plant is mildly toxic to cats, dogs and horses if consumed.

What is Lemongrass?

A staple of Thai and Vietnamese cooking originates in the tropical climates of South India and Sri Lanka. Increasingly popular for its fresh, zingy taste and citrusy aroma, this warm weather loving herb is also rich in essential oils and a staple of aromatherapy.

Part of the Cymbopogon genus, this plant is hardy in USDA Zones 10 and 11. In cooler climates it is best grown as either an annual or a tender perennial, being moved to a sheltered position during the cooler, winter months.

The plant has a clumping habit, producing multiple stalks from its large base. In favorable conditions it can reach up to 5 ft tall and spread 3 to 4 ft wide. Lemongrass is easily identified by the upright, arching shape that its green leaves create.

In the ground, in favorable conditions, these can develop into large plants. 

Are Different Varieties Available?

Unlike many herbs, there are very few named cultivars or varieties. The plant is often simply labeled with its generic name. Despite this, lemongrass plants can be divided into one of two categories:

• West Indian,
• East Indian.

West Indian lemongrass (Cymbopogon citratus) is a popular choice if you want to use the plant for culinary purposes. The West Indian variety has a strong, citrusy flavor.

The East Indian variety (Cymbopogon flexuosus) is also edible and displays an aromatic citrusy scent. However, it is not as rich in flavor as the West Indian variety.

Lemongrass is part of the Cymbopogon genus. Another member of the genus, Cymbopogon nardus or citronella grass, while not edible, is a useful addition to the garden.

Citronella grass emits a pungent odor that deterred insects and pests. It is a popular choice for planting in pots and placing around patios and decked areas.

Despite a similar name the two plants are different in appearance. Citronella grass is green with a red tinge at the base in contrast to the yellow-green lemon grass that has a white base. Citronella grass typically has a muskier or grassier aroma.

Like Cymbopogon nardus, Cymbopogon winterianus is a variety of citronella grass which is similar in appearance to lemongrass. Again it is not suitable for use in the kitchen. An ornamentally attractive plant learning how to grow citronella can help to keep pests away from your prized flowers and vegetables.

How to Grow Lemongrass

Lemongrass plants are commonly sold in garden stores. You can also grow from seed, however seeds are more difficult to find. An easier way to cultivate your own plant is to learn how to grow a new plant from a lemongrass plant purchased in a grocery store.

How to Grow Lemongrass from Seed

This is a pleasingly easy plant to grow from seed. Seeds can be purchased from garden stores or seed catalogs.

Sow your seeds in cell packs or flat Seed Starter Trays filled with fresh potting soil. Moistening the soil before sowing helps the seeds to stick in place. Use a handful of compost to lightly cover the seeds. Do not bury the seeds too deeply, they need light to germinate.

Sow seeds lightly on moist soil 

The temperature around the seeds should be kept around 70 ℉. If the temperature is too cold the seeds struggle to germinate. A VIVOSUN Digital Thermometer enables you to accurately monitor the temperature around your plants.

In good conditions germination typically takes 10 to 20 days.

Continue to protect the seedlings until they are large enough to handle and can be safely transplanted into their final growing position. If you are learning how to grow lemongrass in the garden, wait until the soil and ambient temperature has warmed up and the last frost date has passed before transplanting.

How to Grow Lemongrass from Cuttings

You can learn how to propagate cuttings either from a healthy plant that is already growing in your garden or from a plant purchased at a grocery store. Inspect your plant, looking for firm, fresh stems. These have the best chance of succeeding.

Cut a healthy stalk cleanly away from the plant with a knife or garden scissors. Your incision should be made around 1 inch above soil level. This enables the remaining stalk to produce fresh growth. Cut away the upper part of the stalk, to create a 3 to 4 inch section. Any leaves can also be removed.

Do not cut away the bottom, white part of the stem, if you do this the cutting will struggle to produce new roots.

New roots emerge from the white part at the bottom of the stem.

Place the stems in a glass of fresh water. The thick, white end of the stem should be covered entirely by the water.

Keep the glass on a windowsill, remembering to change the water every few days. This helps to keep the water fresh. Stale water lacks oxygen, meaning that roots struggle to develop and bacterial growth may form.

Once roots have emerged and are a few inches long, transplant the shoots to pots filled with fresh compost. Water and return to the windowsill. Continue to water and apply a fertilizer such as seaweed fertilizer every 2 weeks. Once the last frost date has passed, harden the new plants off before transplanting or placing them outside permanently.

How to Grow and Propagate From a Mature Plant

This is a large plant that forms in a clump. The plant’s clumping growth habit makes it easy to divide mature specimens.

To propagate, dig up the entire clump. If the plant is growing in a pot simply remove it from the pot. Brush away any soil that is still clinging to the root system.

Use a spade or trowel to separate the clump into smaller pieces. Each piece should have a leaf fan that is attached to a narrow bulb-like base with its own set of roots. These pieces can be planted on to form a new clump.

Depending on how large your starting clump is you can either divide the plant into individual bulbs or sections with 5 or 6 bulbs.

Replant immediately either in pots or the garden and water well. Continue to water every day until the divisions are established and new growth is visible.

How to Pot and Repot

In cooler climates these plants are best grown in a pot. This enables you to more easily overwinter the plant, cultivating it as a tender perennial instead of an annual plant.

Your chosen pot should be at least 12 inches wide. A pot of this size is not only able to accommodate the growing root system, it also prevents these top-heavy plants from falling over.

Fill the pot with a good quality potting soil. One that is premixed with a slow-release fertilizer helps to boost your plants growth. You can also work a slow release 6-4-0 fertilizer, such as Milorganite Fertilizer, into the potting soil as you fill the pot.

These plants grow just as well in pots as they do in planters or garden soil. Source: homegrown  by pengrin / CC 2.0

How to Plant

One of the most important parts of learning how to grow lemongrass is correctly planting.

Whether you are learning how to grow lemongrass in the soil, a pot or planter, planting is largely the same. Remember to work in soil amendments before planting. If you are planting outside, wait for the soil to warm up and harden off the plants before transplanting.

Make a hole in the prepared soil large enough to hold the root ball.

Remove the plant from its current container. While this is a robust plant that tolerates some handling, be careful not to damage the root system.

Center the plant in the middle of the hole and backfill with fresh soil. Water well.

Space your plants at least 12 inches apart. Rows of plants can be spaced 18 inches apart.

If you are learning how to grow from seed, the plants are typically ready for harvest 75 to 100 days after sowing the seeds. The more favorable the growing conditions the quicker the plants mature.

Space your plants gives them room to grow into. Source: Lemongrass by lucianf / CC 2.0

Where to Grow Your Plant

These tender plants grow best in conditions that are similar to its natural warm, humid habitat. These plants like lots of heat, light and moisture. In these conditions the plant displays a quick and healthy growth habit.

Even in hotter climates, this plant is best cultivated in full sun. Aim to provide your lemongrass plant with at least 6 hours of daylight every day. Plants placed in too shady a position may become sparse or attract pests.

In warm climates you can grow the plants in the garden. Source: Lemongrass by Kimberly Reinhart) / CC 2.0

These plants do best in hot, humid conditions. If you are learning how to grow lemongrass outdoors, the plant’s requirements are similar to those of a tomato plant. Nighttime temperatures should be over 50 ℉ before you transplant young plants into the garden.

This is a frost sensitive plant. Growers in cooler climates who want to overwinter the plants should grow them in pots. This enables you to move the plants indoors or to a heated greenhouse before temperatures drop below 50 ℉. If you are growing in a larger pot, placing it on a Large Metal Plant Caddy enables you to easily move it around your patio and home.

One of the most important elements to consider when learning how to grow lemongrass is the soil. These plants do best in rich, loamy soil. To improve your soil, work in various amendments such as compost, leaf mold and manure. All of these help to enrich the soil and promote healthy growth.

Companion Plants

Not only is this herb a good culinary plant, it is also a useful companion plant. Rich in citronella, many pests are deterred by the presence of lemongrass.

Lemongrass can grow well alongside other herbs such as mint, lemon verbena and basil. A popular combination, mint and lemongrass can be used to create a natural border to your garden, keeping away pests while attracting pollinators such as bees and butterflies. You can also combine the plants with marigolds for a similar beneficial barrier.

Mint is a good companion plant. 

This reliable herb is a popular companion plant for echinacea. Many pests such as aphids, mites and Japanese beetles can all target echinacea plants, preventing them from flowering. Learn how to grow lemongrass in close proximity to echinacea deters any pests, enabling your echinacea to flourish.

Similarly basil benefits from the effects of citronella in the lemongrass plant. As your basil plant flourishes, scores of pollinators are drawn to the garden.

Many plants that are prone to aphid infections, such as sweet peppers and ginger benefit from being grown in close proximity to lemongrass plants.

Cilantro and lemongrass enjoy a mutually beneficial relationship. Lemongrass deters pests from attacking cilantro plants, while the strong smell of the cilantro deters any pests that may want to target your plants.

Another popular combination is lemongrass, basil and tomatoes. Here the basil helps to sweeten your tomato fruit while the lemongrass deters any pests.

Avoid growing your lemongrass in the same patch of soil as lavender. These plants require regular watering. Too much water can kill you lavender plants.

Another combination that you should avoid is thyme and lemongrass. The growing requirements of these two plants are too different for them to successfully share the same soil. Similarly, sage is a companion plant that should be avoided. Sage prefers a drier soil than lemongrass. If you attempt to keep the two plants happy in the same soil, neither will flourish.

A final herb that you should avoid growing close to lemongrass is rosemary. Like sage, this aromatic herb does best in a drier soil.

Caring for Your Plants

One planted, learning how to grow lemongrass is a pleasingly easy process.

Plants growing in the ground or planters can easily reach a height of 3 to 5 ft and achieve a spread of around 2 ft during the course of a growing season. If you are learning how to grow lemongrass in pots, growth may be more constrained.

Once planted, this is an easy to grow plant. Source: lemongrass by Linda De Volder / CC 2.0

When to Water

One of the most important aspects of learning how to grow lemongrass is getting your watering routine right.

If it doesn’t rain, or you are learning how to grow undercover, aim to give your plants 1 inch of water per week.

Established, mature plants tend to have a good level of drought tolerance so won’t notice if you occasionally miss a week. However, regular watering encourages healthy growth and flavorsome leaves to develop.

A layer of mulch, roughly 3 inches thick, helps to conserve soil moisture. This is particularly useful if you are growing in warmer climates where the soil can dry out quickly. Organic mulches break down over time, further enriching the soil and boosting growth.

Fertilizing Growing Plants

This is a grassy plant. Consequently a nitrogen rich fertilizer is recommended. Applying a slow release fertilizer early in the year steadily feeds your plant throughout the growing season.

For a further boost, manure tea can be incorporated into your watering routing. This adds useful trace nutrients to the soil.

Can I Overwinter My Plant?

Some people like to treat this herb as an annual plant, however you can easily learn how to grow lemongrass as a tender perennial.

The plant is considered hardy in USDA Zones 10 and 11. Here, it remains evergreen throughout the year.

Growers in USDA Zones 8 and 9 may notice that their plants die back in the winter, producing new growth the following spring.

In colder areas you can either move the plants inside for the winter months, if you are learning how to grow in pots, or dig up the clumps and plant them in pots. Again the pots can then be moved inside for the winter months.

For plants moved undercover, reduce watering to once every two weeks. Aim to keep the temperature around the plants over 45 ℉. The following spring, harden off your plants before fully returning to their usual outside position.

How to Prune

If you are learning how to grow lemongrass as an annual plant there is no need to prune. However, if you are treating the plant as a perennial, an annual pruning helps to keep the plant neat and tidy.

This plant naturally dies back in the fall, producing new growth the following spring. If your plants are remaining outside for the winter months, don’t remove the brown leaves. Allowing these to remain on the plant helps to protect it from frost. Instead, prune early in the spring, once your last frost date has passed.

To prune, use shears or garden scissors to cut the plant down to a height of around 6 inches. As it awakens from its winter dormancy, the plant quickly sets up fresh, new shoots.

New growth emerges in the spring. Lemongrass by Joshua Garr / CC 2.0

How to Solve and Prevent Common Problems

Despite its reputation for being an easy to grow plant, there are some potential issues that you should be aware of. Luckily many of these are either easily solved or prevented. Additionally, because it contains citronella, a natural pest-repellent, pests rarely attack the plant.

One of the few pests that do target this plant is the Yellow Sugarcane Aphid (Sipha flava). A small yellow pest, if allowed to inhabit your plants, the Yellow Sugarcane Aphid sucks the sap from the foliage, causing yellow or brown spots to develop.

If you notice any pests on your plants, wash them away with a blast from a garden hose. Persistent infections can also be treated by wiping neem oil onto the leaves.

If you are learning how to grow in pots, you may notice the soil quickly dries out. They are also not as drought tolerant as plants growing in the ground. Water your plants regularly.

Rust can form on wet leaves. lesions | Rust by Scot Nelson / CC 1.0

Rust fungus is one of the few diseases that can affect these resilient plants. Rust diseases can cause brown spots or streaks to form on the leaves. Red or yellow streaks can also develop. Cut away and destroy any affected leaves.

The easiest way to prevent rust fungus is to water your plants with a watering can at soil level. Keep the foliage as dry as possible. Spacing your plants out so that air is able to freely circulate around the plants also helps to prevent rust. Damp or excessively moist conditions can also cause rust to form.

Foliage turning brown can be a sign of insufficient water or fertilizer. Either issue is easily amended. However badly affected leaves should be trimmed away and disposed of on a compost pile. A soil moisture sensor is a useful way to gauge how wet your soil is.

How to Harvest Lemongrass

Both the shoots and the leaves have a number of culinary and other uses. For example, the plant is also commonly used in aromatherapy where its fragrance helps to elevate your mood and as an essential oil.

Plants can be harvested as soon as they are 12 inches tall and the stem bases measure half an inch thick. Use a sharp scissors or knife to cut away what you need.

Cut the leaves when they are around 12 inches long. Fresh leaves by Andrea Nguyen / CC 2.0

Aim to cut so that around an inch of the leaf is left at the bottom of the plant. Allowing a section of leaf to remain in place encourages new growth to emerge.

If you want to harvest the plant’s stalks, wait until they measure at least half an inch in diameter. Stalks that are thinner than this tend to still be fibrous.

Use a knife to cut away the stalk. Make your incision about an inch above ground level. Carefully separate the harvested stalk from the rest of the plant. This process can be repeated until you have enough stalks.

If you want to harvest a lot of stalks, it may be easier to simply pull the plant from the ground. You can do this at any point after the plant matures enough to be ready for harvest. This is a particularly useful option for growers in colder areas who know that their tender plants will soon fall victim to the fall frosts.

Preserving Your Harvest

While they are best used fresh, the leaves and shoots freeze surprisingly well.

To freeze the leaves or shoots, begin by cutting them down into 3 to 4 inch long sections. The pieces should be long enough to fit into an airtight container or Ziploc Food Storage Bag.

Seal the sections in your container and place in your freezer. Correctly stored, the leaves or shoots can keep for up to a year.

To use the frozen pieces, remove from the freezer and defrost. When thawed the pieces can be chopped up and used in the same way that you would use fresh pieces.

Alternatively, you can dehydrate the plants. Growers in dry climates can simply cut the stalks or leaves up into 3 to 6 inch long sections and place them spread out on a wire cooling rack to dry out.

In a warm, dry location the plants dehydrate within 2 weeks. The pieces are dehydrated when the moisture has evaporated and they feel rigid. Discard any pieces that develop mold.

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You can also dehydrate the pieces in a food dehydrator or oven. If you are using an oven, set it to its lowest setting and place the pieces, spread out on a baking tray, inside for 2 to 3 hours.

Dried pieces can be stored in an airtight container or bag, in a cool, dry location. Here they keep for up to 6 months.

Learning how to grow lemongrass is a straightforward and rewarding process. As well as filling your garden with ornamental interest and color, the plants can also be used in the kitchen or to create a soothing essential oil. Now that you know how to grow the plant, why not add lemongrass to your garden?