This rapidly growing plant has dense grassy leaves sprouting from cane-like stems. It is intolerant of frost and therefore can live outside year round in mild climates, or can be grown in containers and overwintered indoors. It is a very thirsty plant, enjoying frequent waterings and high humidity. The lemongrass plant is grown for a number of reasons, including for culinary use and the medicinal benefits of the essential oils occurring naturally in the plant.
Lemongrass Plant Quick Facts
|Origin||Sri Lanka, Malaysia|
|Scientific Name||Cymbopogon citratus|
|Common Names||Lemongrass, Serai, Oil grass|
|Ideal Temperature||65- 85° F|
|Toxicity||Non-toxic to humans, both stalks and leaves are edible. Toxic to dogs, cats, and horses (ASPCA)|
|Light||Bright, direct light|
|Humidity||Moderate to high humidity|
Caring for Your Lemongrass Plant
Lemongrass plants grow quickly, especially in warm, humid conditions, so they need plenty of water to fuel their rapid growth. Lemongrass planted directly into the ground will need a watering schedule that reflects the type of soil it is in. A loam-based soil will retain moisture better than sandy soil, so it will need to be watered more frequently.
You should aim to mimic the natural environment where lemongrass natively grows, in Southeast Asia. In its natural habitat, lemongrass would have continuously moist and rich soil, so don’t allow the plant’s soil to dry out, but also take care not to overwater the plant. If in doubt, check the first inch or so if the plant's soil with your finger, and if it is dry, then the plant needs to be watered. The top layer of soil should be allowed to dry out in between waterings, but beneath that, where the roots lay, should always be moist. When watering, water heavily to ensure the water seeps down through the soil and the roots can get fully soaked.
If you have grown your lemongrass in a container, whether this is inside or outside, the watering requirements will be slightly different. Lemongrass in a pot will likely need watering more frequently than that grown in the ground. This is because moisture tends to evaporate from the sides of containers, but also because potted plants rely solely on the moisture they receive through watering, whereas plants grown in the ground can spread their roots further to seek out moisture in the nearby soil.
To keep your potted lemongrass plant healthy, you will likely need to water it every day or two throughout spring and summer when it goes through its growing period. Lemongrass plants will become almost dormant over winter, so you will need to cut back the watering schedule by at least half during this time. Container plants are also more susceptible to root rot than those grown in the ground. Ground grown plants have more means to drain water away from their roots if there is too much moisture in the soil, whereas the roots of container plants have no escape if their soil becomes excessively wet.
Although lemongrass loves to live in moist soil, it is still susceptible to root rot, so you should be careful to avoid overwatering. Root rot destroys the roots of a plant, leaving them unable to absorb moisture or nutrients and essentially starving the plant. If this happens, it usually causes so much damage that the plant cannot recover. To prevent overwatering, only water your lemongrass plant if the top inch of soil feels dry to the touch.
Lemongrass, in its native habitat, enjoys long and hot growing seasons and will grow best in areas that can replicate these conditions. If you live in a mild climate year round, then you can plant your lemongrass directly in soil in your garden and enjoy the perennial all year long. To survive outside throughout winter, temperatures will need to remain above 40° F, with little fluctuation in temperature.
If you do not live in a mild climate where this is possible, then lemongrass should be kept in containers and brought inside when temperatures get too low. Otherwise, lemongrass plants will die over winter, though with the right care, they will be able to start fresh growth when spring rolls around again.
If you keep your lemongrass plant inside, regular home temperatures will be fine for the plant. If you are comfortable in your home, then your plant will be too. As the plant does not like to get too cold, make sure you don’t keep it near drafty areas, such as entryways, cooling vents, or open windows. Also, be sure to keep it in a well-used part of your home that will be heated throughout winter. If you place the plant in a rarely used guest room or storage room that doesn’t get heated often, then you may inadvertently allow the plant to die from too low temperatures.
This plant is one of few that enjoy full, direct sun, so it’s perfect to set in a bright sunny window or an unshaded area of your garden if you want to keep it outside. Lemongrass will need plenty of bright sunlight even in winter, so ensure it has access to natural light; otherwise, the stalks will turn brown. If situated in an ideal bright spot, you will see rapid growth during summer months from your lemongrass. If your plant lives in an area with bright but indirect light, it should still grow well, but not as quickly. Lemongrass does not like to be kept in low light or shaded areas and will suffer if it is kept in these conditions.
In their natural environment, lemongrass plants experience quite humid conditions. They will benefit from living in high humidity in your home or garden, though as long as light, temperature, and water conditions are right, humidity shouldn’t be too much of a concern and regular humidity found in homes will do just fine. Just take care not to put the plant in areas of dry air, such as near heating vents, as this can dry the plant out very quickly and lead to brown stalks.
If you want to increase the humidity of the air around your lemongrass plant, you can spray it with a water mist, or use a pebble tray with water around the base. Either of these options works well to increase humidity in the targeted area around your plant, and the lemongrass will benefit from the extra moisture in the air. If you wanted to increase humidity in your whole room, you could use an electric humidifier. This will be a good option if you have several houseplants that like to be in humid conditions.
If you are growing lemongrass to use as an herb, then cutting it back for use in your cooking will help to keep the plant from growing excessively. That being said, lemongrass grows very rapidly in the right conditions, and even someone who uses lemongrass frequently in their recipes may still find the need to trim back the plant to keep it from becoming overgrown.
Pruning of lemongrass is best done in early spring before it enters its phase of rapid growth. If the plant has gone dormant over winter, then you will likely have a very gray-brown looking plant at this point. Start your pruning by pulling out any browned or dead looking stalks. Sometimes, these will have unattached themselves at the root, and they will pull out very easily, whereas others may still be attached at the root and need a bit of a tug. Either way, any dead material needs to be removed from the plant. Once you have only green stalks remaining, you can then prune these back to a height you are happy with.
Lemongrass responds very well to pruning and will react by rewarding you with lots of fresh new growth, so don’t be worried about over pruning. The lemongrass plant can grow to heights of 6 ft, so it is quite common to continually cut back healthy stalks to around 3 ft in height to keep it at a manageable and neat size. If your plant went completely dormant over winter, you might find that all of the leaves appear brown and dead. If this is the case, cut off the leaves right back to the stalks where they are white and tender. This may look severe at first, but the lemongrass plant should recover well and quickly become full and healthy again in spring and summer.
Keeping lemongrass in containers is a good idea if you like to enjoy lemongrass in your cooking all year round, as unless you live in a very warm climate, lemongrass grown as an outdoor perennial tends to die off each winter. Container lemongrass has the portability to be taken inside over winter and kept alive. Due to the fact that lemongrass grows so quickly, repotting is a necessary and frequent occurrence when kept in containers.
If you have kept your lemongrass in a container outside during summer, then repotting it before colder temperatures set in when you bring it inside is a good idea. An ideal pot size for lemongrass is around eight inches in depth and eight inches in diameter. Any bigger than this, and the lemongrass will grow to a size that isn’t manageable to keep indoors.
To repot, simply grab hold of the plant close to the soil and ease it out of the container. If the plant is particularly root-bound, then this could be a struggle, and in some cases, you may need to crack the pot in order to release the plant. Once you have the root ball out of the pot, you need to separate it in half or thirds. You can do this using a sharp serrated knife or garden cutting tools. Ensure that each new root ball you create has a good chunk of grass still attached. You can then proceed to house each new smaller plant in a pot filled with fresh soil. Water the plants deeply and sit them in a bright and warm spot inside to overwinter.
As a quick-growing and foliage-dense plant, lemongrass benefits from a fertilizer high in nitrogen, which encourages leaf growth. Both indoor and outdoor lemongrass plants should be fertilized during their growing period in spring and summer. Use a liquid fertilizer on a monthly basis, and then, cease feeding your lemongrass plant completely during fall and winter when the plant slows growth or becomes dormant.
Lemongrass grows rapidly, so the most popular method of propagation is by division. Once your lemongrass plant reaches a good size, which it should after just one growing season, you can divide it up to create several new plants.
To make this process easier you can harvest the plant first, cutting the stalks back right down to the soil. Though this might look severe initially, it will make the lemongrass much less hassle to handle, and due to the plant’s ability to grow rapidly, you will have a full-sized lemongrass plant again in no time. To propagate the plant, simply remove it from its pot and divide the root ball into several new plants using a knife.
If your lemongrass has been growing in the ground, you can use a shovel to carefully dig it up, and divide it in the same way. Be careful not to harm too many roots when digging up your plant, but some damage is likely to occur, and this should be expected. Lemongrass plants recover quickly, so don’t worry about this too much. Plant your new smaller lemongrass plants in containers or back directly into the soil of your garden. If you are planting them in the ground, make sure they are a minimum of three feet apart to accommodate their new growth. Lemongrass plants typically grow to three feet in width outdoors, and six feet high. In containers, you can limit this growth by keeping them in smaller pots and continually cutting them back.
If you don’t already have a lemongrass plant to divide, then you can propagate with stem cuttings. This is an incredibly easy process with high rates of success, and you can simply use cuttings of the plant from the grocery store. When selecting a lemongrass cutting, look for a stalk with as much of the bulb attached as possible.
In some cases, you may find stems which also have a few root fragments attached, and these will work even better for successful propagation. Once you have your stalk, place it in a glass or jar with around an inch of water in the bottom, ensuring the bulb end of the stalk is submerged. Keep the stalk in a warm and bright location, and wait for roots to appear. The process should take around three weeks, with leaves growing from the top end as roots appear at the bottom end.
Once roots are a few inches in length, you can plant the cutting either directly into the ground or in a small container pot. Use a loam-based soil for the best moisture retention and continue care as usual (Royal Horticultural Society).
Lemongrass is commonly grown as a culinary herb and used in Asian inspired recipes. To harvest the herb for use in cooking, you will need to locate a suitable stalk and cut it low down, as close to the soil is possible. Stalks which are at least a quarter of an inch thick will be ideal. The tender part of the stalk closest to the base of the plant is considered to be the most flavorsome and edible, so you shouldn’t cut the stalks off too high if you intend to use them for cooking.
If your plant is kept indoors all year round, then you can harvest it at any point. Lemongrass that remains outside for all seasons is best harvested before the first frost arrives in fall. There are numerous recipes you can follow to use lemongrass to add flavor to dishes, which usually involve slicing up of crushing the stalks. Though lemongrass is best used when fresh, it also freezes well and can be stored this way for up to six months.
While the stalks are the most commonly used part of the plant, the leaves are also edible. They can be dried and used to flavor tea or soup. Lemongrass tea is said to have soothing properties that can help people sleep (Plant Village- Penn State University).
Lemongrass is also used as a mosquito deterrent as it contains citronella. If you wish to use lemongrass to discourage mosquitoes from buzzing around your garden, you should plant it strategically in areas that are often frequented by people, such as along paths or around terrace and seating areas. You can also snap stalks off the plant and open them up to reveal their scented oils. This can then be rubbed onto the skin to be used as a natural alternative to insect repellent. You can also rub the inside of the stalks on pets’ fur to help keep them free of annoying pests.
Lemongrass plants are also used as a whitefly repellent. If you have other plants that get targeted by whitefly, then you can plant lemongrass nearby by to discourage this from happening in the future.
How do you use your lemongrass plant? Let us know in the comments and share this article with others who may be interested in growing lemongrass!