Lemon Grass 
Cymbopogon ciatrus
Family Poaceae
A tall Perennial plant that is a grass, apparently there are about 45-55 species of grass in this genus. They are tall with a swollen base and a lovely lemony fragrance. Lemon grass is now planted in most tropical and temperate areas around the world and widely used for its essential oil, in aromatherapy, addition in foods, companion plant and a variety of medicinal uses. 
Growing Guide
Ideal Environment 
They generally prefer warm, moist and sunny areas with fertile, rich, well draining soil. Many sources also recommend mulching to keep the area moist and warm.
How to Plant 
Can easily grow 50cm high and up to 1.5 meters in the garden so provide enough space. They can also grow in pots quite easily.
How to Water 
Water Lemon grass regularly during the warmer months (well watered at least once a week). Reduce watering in the winter to once every couple of weeks.
Companion Planting 
Lemon grass repels many insects including mosquitoes, however in my experience you probably have to plant allot to really get the effect or at least a border around a porch or similar. Lemon grass can work well as a companion plant in the herb garden and several sources list some herbs and other lemony plants.
How to Propagate 
You can propagate lemon grass from stalks that have a little root on them. You can also divide existing plants easily.
You can also grow them from seeds but it takes a bit of time.
How to Harvest 
You can start harvesting once the plants reach about knee heights and the stems are at least as thick as a finger. Usually you harvest a stem or two at a time, just cut it out of the base of the plant with a sharp knife. The outer leaf casing is peeled off and the tender stem in the middle is usually used.
Information & Research
Key Constituents 
Volatile oil with citral (about 70%) and citronella (1).
Luteolin, flavonoids quercetin, kaempferol and apiginin. The phenolic compounds elimicin, catecol, chlorogenic acid, caffeic acid and hydroquinone are also isolated from the plant (16).
Key Actions 
Sedative (1), Antioxidant, Antiseptic, Carminative, Digestive, Insecticide, Stimulant, Tonic (15). Anti-fungal, anti-inflammatory, anti-malarial, anti-mutagenicity, anti-mycobacterial and anti-oxidant effects (16).
Research 
Studies indicate that Lemon grass has various pharmacological activities such as anti-amoebic, antibacterial, antidiarrheal, antifilarial, antifungal, anti-inflammator, antimalarial, anti-mutagenicity, anti-mycobacterial, antioxidants, hypoglycemic and neurobehaviorial have also been studied (16).
Preparations & Uses
Parts Used 
The tender stem is used in foods and infusions (mostly the first 20cm from the swollen base).
The leaves can also be used in decoctions and the essential oil is taken from the whole plant.
Preparations 
Infusions are most commonly used.
You can use 1-4 gram of dry material per cup of hot water or 1 mashed root (15), or 1 tablespoon fresh plant material per cup (1, 3). It is also great in soups, curries and Thai food.
Uses 
Lemongrass can be taken as a tea for digestive problems. It relaxes muscles of the stomach and gut, relieves cramping and flatulence (1). Other known uses include: fever reducing, poultice for arthritis, Anxiety, relieving nasal congestion, Fatigue, Headaches, High blood pressure, Infection, Insomnia, Pain, Ringworm and toothaches (1, 15).
Other Plants
