Lemongrass is a fragrant, stalky herb widely used in culinary and aromatic applications, known for its bright, citrusy scent. Lemongrass is botanically classified as a “tender perennial,” meaning its designation depends entirely on the climate where it is grown. This tropical grass thrives in heat, and its ability to survive year-round is linked to the absence of cold weather. For most gardeners, the plant’s sensitivity to frost dictates its classification as an annual that must be replanted each spring.
Understanding the Tender Perennial Classification
A tender perennial is defined as a plant capable of living for more than two years, but which cannot tolerate freezing temperatures. Lemongrass (Cymbopogon citratus), native to tropical regions, is extremely cold-sensitive. The plant begins to suffer damage when temperatures consistently drop below 45°F, and frost will entirely kill the plant structure.
Because of this low-temperature threshold, lemongrass functions as a true perennial only in consistently warm, frost-free climates (USDA Hardiness Zones 10 and 11). In these zones, the plant remains in the ground, growing in large, dense clumps. However, in Zones 9 and colder, where winter frost is certain, the plant must be treated as an annual and will die back unless protective measures are taken. This necessity of protection or replanting causes many gardeners to view it functionally as an annual herb.
Overwintering Techniques for Colder Climates
Gardeners in cooler zones can maintain lemongrass perennial status by employing overwintering techniques. The most common method is growing the plant in a container, allowing easy relocation before the first frost. Before moving the potted plant indoors, cut the foliage back severely (often to six inches) to help the plant conserve energy during its semi-dormant phase.
The trimmed plant should be placed in a cool, dimly lit area, such as a basement or garage, where temperatures remain consistently above 40°F to 50°F. During this dormant period, the plant requires very little water, needing only occasional watering (perhaps once a month) to prevent the soil from completely drying out. Alternatively, gardeners can dig up and divide the plant’s rhizomes before a hard freeze, storing them in a container with moist peat moss or sand until spring.
Essential Requirements for Healthy Growth
During its active growing season (spring through fall), lemongrass requires specific inputs to thrive and produce flavorful stalks. The plant needs a location that receives a minimum of six to eight hours of direct sunlight daily. Sufficient light is directly correlated with the plant’s vigor and the intensity of its signature lemon flavor.
Lemongrass performs best in rich, loamy, well-drained soil, as soggy conditions can quickly lead to root rot. It requires consistent moisture throughout the summer, often needing deep watering, especially when grown in containers. Because it is a grass, it benefits from regular feeding with a high-nitrogen fertilizer during the peak summer months to support rapid growth and dense foliage.