Lemongrass plant in a 3 gallon container. Lemongrass is a tropical herb packed with strong citrus flavor. The lemon taste is prized in Asian cooking, as well as in teas, sauces, and soups. In the garden, lemongrass forms a tall, grassy clump 3 to 5 feet tall. Its appearance rivals that of many ornamental grasses and can easily fulfill a similar role in the landscape.