Lemon grass (Cymbopogon citratus) is grown as a perennial in USDA horticultural zones 8 to 11 and as an annual or container plant everywhere else. It is a clumping grass that grows to 4 feet tall and wide. The bulbous stems are used in Asian and Caribbean dishes, where they are smashed to release the oils. Of the 55 different varieties of lemon grass, only two--East Indian lemon grass and West Indian lemon grass--are used for cooking. It is rarely grown from seed and is most often sold as transplants. The lemon grass sections sold in the store have a bulbous end where the roots are formed. They can be rooted for planting by setting them in a glass of clean water for about two weeks.
Find a location in the garden that gets more than six hours of sun each day. The location needs to be well-drained, as lemon grass cannot sit in waterlogged soil for long periods of time. If you are planting more than one plant, the plants need to be spaced 3 or 4 feet apart. They will grow to full size in one season.
Clear the area of weeds, because lemon grass does not compete well with other vegetation. Add a 1-inch layer of compost over the planting area along with the recommended amount of granulated organic fertilizer. Look on the fertilizer label for recommended fertilizer amounts to add to the soil. Gently work the fertilizer and compost into the top inch of soil with a hoe, and rake the area smooth.
Plant the bulbous end 1 inch deep in moist soil. The soil must be kept moist but not wet until the lemon grass is actively growing. You will see new growth appearing around the original plant in a few weeks.
Water the lemon grass every few days if the weather is unusually dry. Otherwise water once a week during the summer if there is no rain. Don't water during the winter as it may cause the roots to rot.
Prune the lemon grass when it turns completely brown during the winter by shearing all foliage off with a hedge trimmer to a few inches above the ground. There is no reason to prune the foliage if you live in an area where the plant remains green all year. Lemon grass can be divided by chopping off a root section containing bulbous ends with a shovel or ax. Replant the single bulbs, or clumps of bulbs, in another location in late winter or early spring.