Lemongrass is a popular herb, used in cooking and for its aroma. Many gardeners wonder about its growth habits and if it poses a risk of becoming invasive in their landscapes. This article explores the nature of lemongrass growth and provides guidance on managing its spread.
Understanding Lemongrass Growth
Lemongrass (Cymbopogon citratus) is a perennial tropical grass that forms dense clumps. It expands primarily through underground rhizomes that grow horizontally, sending up new shoots around the parent plant.
Its arching, strap-like leaves can reach 3 to 5 feet tall, with a single clump growing up to 2 feet wide in a season. This vigorous growth can quickly fill a garden bed if left unchecked. It thrives in warm, humid conditions with full sun and consistent moisture.
Is Lemongrass Truly Invasive?
The term “invasive” in an ecological context typically refers to non-native species that cause environmental or economic harm by outcompeting native plants. While a rapid and vigorous spreader in a garden setting, lemongrass is generally not classified as ecologically invasive in most regions. As a tropical plant native to southern India and Sri Lanka, its ability to become invasive is limited in cooler climates.
Lemongrass is considered an aggressive spreader rather than a true invasive species. This means it can quickly colonize available space within a cultivated garden, potentially crowding out less vigorous plants. Its rapid expansion is particularly noticeable in warm, frost-free climates (USDA Zones 10-11) where it can grow as a perennial and does not experience dormancy. In colder zones, it is often grown as an annual or overwintered indoors, which naturally curtails its spreading potential.
Managing Lemongrass Spread
Several strategies can manage lemongrass spread. Container planting is effective, as pots restrict rhizome spread. A large pot (at least 12 inches in diameter or 5-gallon size) provides ample room while confining the plant.
For in-ground planting, root barriers around the clump prevent outward expansion. Barriers should be deep enough to deter rhizomes. Regular division of mature clumps (every few years) also manages size and vigor. This involves digging up the plant, separating sections with intact roots, and replanting or sharing. Strategic placement (e.g., away from other plants) and regular harvesting of outer stalks also help control size and encourage new growth.
Benefits of Growing Lemongrass
Despite its aggressive growth, lemongrass offers many advantages, making it a desirable garden addition. Its culinary uses are extensive, providing a distinct lemony flavor for teas, soups, curries, and other dishes. It also repels insects, particularly mosquitoes, due to compounds like citronella.
Beyond practical uses, lemongrass adds ornamental value with graceful, arching foliage, creating a tropical aesthetic. It is also used in aromatherapy for its scent and in natural medicine for traditional remedies. These benefits often outweigh the need for routine management.