Lemon grass is widely used as an herb in Asian (particularly Vietnamese, Hmong, Khmer, Thai, Lao, Malaysian, Indonesian, Philippine, Sri Lankan) and Caribbean cooking. It has a citrus flavour and can be dried and powdered, or used fresh. The stalk itself is too hard to be eaten except for the soft inner part. However, it can be finely sliced and added to recipes. It may also be bruised and added whole as this releases the aromatic oils from the juice sacs in the stalk. The main constituent of lemongrass oil is citral (citronella oil), which makes up around 80% of the total.
The oil extracted from lemon grass, citronella, is used as a mosquito repellent in insect sprays and candles, and also in aromatherapy.
If you don't use them very often, freeze lemongrass stalks to prevent them drying out completely.