The tropical lemon grass plant (Cymbopogon citratus) is known for its strong citrus flavor. A grassy herb that grows in tall clumps, up to 5 ft in height, it is just as suited to use in an ornamental border as in a herb garden.
Commonly used in teas, soups, seafood dishes and Asian cuisine, this vigorous herb is commonly sold in grocery stores. However, it is also pleasingly easy to cultivate. Here is everything you need to know.
A large grassy herb. With careful cultivation you can also grow the herbs in containers and as part of a herb garden.
How to Root Lemon Grass
These herbs belong to the same plant family as both wheat and corn. While Cymbopogon citratus has 55 recognised varieties only two cultivars are classified as lemon grass. These are normally labeled East Indian and West Indian lemon grass.
Whichever variety you grow, planting and caring is pretty much the same.
You can purchase a plant from your local diy or garden center. You can also purchase and root fresh lemon grass from your grocery store.
To root a grocery store bought herb as soon as you get home trim away about 2 inches from the top of the stalks. Also peel or cut away anything that looks unhealthy or dead.
With a little time and effort you can easily root store bought herbs.
Place the remaining, healthy stalks in a glass of shallow water. Unlike a wide bowl, a tall glass provides support, helping the stalk to stay upright. Place the glass close to a sunny windowsill.
Remember to regularly change the water every few days. Constantly refreshing the water helps to keep the stalks healthy and prevent fungal growth.
In a few weeks small roots begin to emerge from the bottom of the stalks. Allow the roots to grow to a decent length, at least an inch, before transplanting.
How to Plant
In the warmer USDA zones you can plant these herbs outside. They are hardy in zones 10 and warmer. In cooler areas the herb can either be treated as an annual or grown in containers. Place the containers in a sheltered position for the fall and winter months, before temperatures drop below 40 ℉.
While lemon grass happily thrives in containers, the herb does have a vigorous growth habit. This means that you will need to regularly divide and repot container growing plants.
To plant fill a pot roughly 8 inches wide and deep with fresh, general purpose potting soil. The container should be clean and have drainage holes in the bottom.
Make a hole in the center of the pot and position the lemon grass. The plant’s crown should sit just below the surface of the soil. When you are happy with the position of the herb, fill the hole and firm down the soil.
Place the pot in a sunny position, such as a windowsill or a patio, and water well.
How to Repot
The best time to repot is in the fall, after the herb has ceased growing for the year. Depending on how quickly your herb grows you may need to divide and repot it every year or two years.
Keeping the plant in a pot roughly 8 inches deep and wide such as these ZOUTOG Pots gives it room to grow while not allowing it to become overly large.
To repot, carefully remove it from the container. Squeezing the side of the container helps to loosen the earth, making removal easier.
Once the plant has been removed from the container inspect the root system for signs of disease. Particularly large root systems may need to be divided. To do this, use a sharp knife or a trowel to cut the root ball into roughly even sections. Each section should have a healthy amount of roots and some grass attached to it.
Fill 8 inch containers with fresh soil. Plant one division per pot as described above. After planting, water well and place in a sunny position.
When potting or repotting always use a clean container and fresh soil. This helps to keep plants healthy and disease free.
Planting in the Ground
While the plant tolerates a range of conditions a pH profile of 6.5 to 7.0 is ideal. If you are unsure of the makeup of your soil, a soil testing kit is easy to use and provides you with valuable information.
Soil that is too acidic or alkaline should be amended before planting. Alternatively plant in planters or containers.
With a good shovel, dig the soil over and remove any weeds before planting. Digging over the soil helps to break up clumps and improve drainage. You can also use this opportunity to work in some organic matter, such as compost or well rotted manure.
When the soil is ready, dig a hole large enough to hold the plant. Position the lemon grass in the hole. The top of the root system should be in line with or slightly below the level of the soil. Backfill the hole and water well.
If you are planting more than one lemon grass, space them roughly 24 inches apart.
Work the soil over before planting, breaking up clumps of earth and removing weeds and stones. This helps to improve drainage and also gives you the opportunity to enrich the soil by working in organic matter.
Caring for Lemon Grass
A full sun loving plant, once planted, care is pleasingly straightforward.
Originating in South East Asia, lemon grass prefers hot, humid weather. In warm areas the plants can grow quickly. Be careful if you are growing outside, temperatures below 40 ℉ can kill the plant.
To keep humidity levels high regularly water and mist the foliage. You can also place pots on humidity trays or saucers filled with pebbles and water. If you do decide to use a humidity tray, ensure that the pot isn’t contacting the water. This can lead to soggy soil and root rot.
When to Water
Water regularly to keep your herb happy and healthy. Never allow the soil to dry out. In its natural habitat these plants grow in soil that is moist and rich. Replicating these conditions as best as possible gives you the best chance of growing a healthy plant.
In warmer climates, where growth is fast, or if sited in loose, sandy soils these herbs may require more frequent watering. Placing a layer of organic mulch on top of the soil can help soil moisture retention.
Knowing when to water can be tricky. To gauge the dryness of your soil, stick your finger in the soil. If it is dry to the first knuckle it is time to water. A soil moisture meter, such as the yoyomax Soil Test Kit, provides a more scientific way of checking the moisture content of your soil.
Organic mulches help the soil to retain moisture. As they break down the mulch restores nutrients to the soil, further benefiting your plants. Remember to regularly reapply the mulch as it breaks down.
The best time to water the herb is either in the early morning or in the late afternoon.
For a low maintenance alternative, try planting in a self watering pot. These keep plants hydrated even if you are too busy or forget, to water them.
When watering, water well. If you are growing in containers, water until water seeps through the drainage holes in the bottom of the pot.
In the summer plants may require watering every day. Depending on conditions, during the fall and winter months the amount of water you give can be reduced by about half.
Do I Need to Fertilize?
If you are growing as an annual in rich soil and regularly mulching with organic matter, there is no need to fertilize.
Plants growing in containers, or kept for more than one year require some fertilizing. Lemon grass is a heavy feeding plant, it is particularly reliant on nitrogen. Regularly apply a balanced general purpose fertilizer throughout the growing season.
Depending on how quickly your herb is growing, apply the fertilizer once every two weeks to once a month during the growing season. The faster the herb grows the more nutrients it uses. Fast growing plants require more frequent fertilizing than slower specimens.
How to Prune
Particularly in warm conditions, these herbs have a vigorous growth habit. Even if you regularly cut the stalks to use in various teas or recipes the plant’s rapid growth habit may mean that you also need to prune it.
Pruning with sharp garden scissors on a regular basis helps to keep the spread of foliage under control.
The best time to prune the plant is in early spring before it begins producing new growth. Begin by removing any dead or damaged foliage. Allow only green and healthy stalks to remain.
Once you have removed the brown foliage use a garden scissors to cut the plant down to a more manageable size.
Don’t be afraid of over pruning. Thanks to its quick growth habit the plant tolerates a harsh pruning.
Remember to clean your tools after using them. This helps to prevent disease from accidentally spreading around the garden.
If you are planting outside, in USDA zones 9 and cooler the herb should be treated as an annual. Alternatively grow the plant in a container. As temperatures begin to fall towards 40 ℉, move the containers to a sheltered position.
A greenhouse or a sunny windowsill is an ideal place to overwinter your plants. Your chosen position should also have good air circulation. This helps to prevent downy mildew and other problems.
Companion planting is the practice of growing mutually beneficial plants together.
Lemon grass contains citronella. This is an essential oil that is known for its ability to repel pests such as mosquitoes. If a mosquito does bite, snap a leaf from the herb and rub the oil onto the skin.
Like a number of other plants, lemon grass is known to repel pests such as whiteflies from other, nearby plants.
Many people like to grow lemon grass in containers around their patio to keep the areas pest free during the summer months. The plants also work well as part of a herb garden.
Complimentary herbs include:
Originating in Asia, lemon grass also does well alongside traditional plants such as cucumbers or mangos. Fennel and onion are two other reliable companions. Ginger and turmeric also do well when planted close to lemon grass.
Lemon grass is a good companion for a number of herbs, ornamental flowers and fruit and vegetable plants.
Common Problems and How to Solve Them
Once planted this is a pleasingly problem free plant. Most pests are put off the lemon grass plant by its citrusy aroma.
For growers, the most common problem is foliage turning brown. This can be a sign that the plant is lacking in water or nutrients. This particular herb is a heavy nitrogen feeder. A general purpose feed should help to maintain nitrogen levels. Mulching with organic matter also helps to keep the soil rich in nutrients.
Brown foliage can also be a sign of rust. As well as turning foliage brown, rust also causes faint yellow spots to appear on the foliage. Brown pustules may also become visible. If left untreated rust can cause plants to fail and die.
Rust thrives in humid conditions, unfortunately for us so does the lemon grass plant.
Adopting good growing practices such as mulching, pruning away diseased leaves and watering the soil not the foliage all help to prevent rust. Spacing the plants so that air can freely circulate also helps to keep plants healthy.
Finally, brown foliage may be a sign of leaf blight. This can cause red-brown spots to form on the edge and tip of the leaf. Prune away infected leaves. A fungicide can also be applied.
How to Harvest
You can harvest lemon grass at any time during the growing season. In cooler areas the herb is best harvested from mid to late summer.
Harvest older stalks first. These are usually a quarter to half an inch thick. Harvest stalks that are about 12 inches tall and around half an inch thick.
The edible part of the stalk is at the bottom. Harvest by twisting or snapping the stalk as close to the root as possible. Discard any woody parts. Leaves can also be discarded or kept and dried for use in soups or teas.
While it is best used fresh, you can freeze lemon grass for up to 6 months.
Lemon grass is an easy to grow herb that can bring ornamental interest to a garden.
An attractive ornamental plant, or a useful herb for a range of teas and meals, the lemon grass plant is a reliable addition to any garden. Best grown in containers the herb can also be grown as a houseplant on a sunny windowsill.
Once planted as long as you remember to water regularly, lemon grass is an unfussy, easy to grow plant.