Lemongrass (Cymbopogon citratus) is an aromatic tropical grass prized for its distinct citrus flavor and scent. It is a staple ingredient in many Southeast Asian cuisines, used in teas, curries, and soups. Its essential oils are also used in aromatherapy and as a natural insect repellent. Whether this plant returns annually depends entirely on the region’s winter climate.
Lemongrass Classification: Perennial Nature and Climate Dependence
Lemongrass is a tender, clumping perennial grass, meaning it can live for more than two years. This capacity is only fully expressed in climates that mimic its native tropical environment. The plant thrives in consistently warm conditions and is extremely sensitive to cold temperatures and frost.
The ability of lemongrass to grow back annually is directly tied to the USDA Hardiness Zone. It is a reliable perennial only in the warmest regions, specifically zones 9, 10, and 11, where temperatures rarely fall below freezing. In these mild climates, the plant remains outdoors year-round, continuing to grow or resting through a short, cool period.
In areas classified as Zone 8 and colder, where the ground freezes or temperatures consistently drop below 40°F, lemongrass is treated as a summer annual. The plant’s root structure cannot survive the deep cold, causing the entire clump to die off. Gardeners in these cooler zones must replant it each spring or adopt specific strategies to preserve the existing plant through the winter months.
Strategies for Overwintering Lemongrass Indoors
For those in colder climates who wish to save mature plants, overwintering them indoors is a practical solution. The process must begin before the first expected frost, when nighttime temperatures fall below 45°F. Start by carefully digging up the entire clump, preserving as much of the root ball as possible.
Once the plant is lifted, trim the foliage back significantly, leaving only about six inches of stalk above the root crown. This reduction minimizes the plant’s need for light and water during indoor confinement. Repot the trimmed root ball into a container using fresh, well-draining potting soil with adequate drainage holes.
There are two main approaches for indoor survival: keeping the plant semi-dormant or attempting to keep it actively growing. The easiest method is to encourage dormancy by placing the potted plant in a cool, dark location, such as a garage or basement, where temperatures remain consistently between 50°F and 60°F. During this dormant period, reduce watering to only once a month, providing just enough moisture to keep the root mass from drying out. If a bright, south-facing window or a grow light is available, the plant can be kept in a warmer room (above 60°F) and allowed to continue slow growth, requiring more frequent watering and light.
Starting New Lemongrass Plants
If overwintering fails or a gardener wants to expand their stock, new lemongrass plants are easily started using two methods. The most common and quickest approach is propagation from store-bought stalks found in the produce section. Select fresh stalks that have the entire base intact, as this is the part that develops roots.
To initiate root growth, trim the top of the stalks and place the bases in a glass of water on a warm, bright windowsill. The water should be changed every few days to prevent rot and maintain oxygenation. Within two to three weeks, small roots will begin to emerge from the base. Once the new roots are approximately one to two inches long, the rooted stalks are ready to be transferred into a pot filled with soil.
Alternatively, lemongrass can be started from seed, though this method is slower. The tiny seeds should be sown thinly on the surface of moist, well-draining seed-starting mix in early spring. Lemongrass seeds should not be covered with soil, as they require light to germinate. Germination typically occurs within 10 to 14 days, and seedlings can be transplanted outdoors once all danger of frost has passed.