The true citronella plant is a perennial grass similar to Lemon Grass, to which it is closely related. It is not the little scented geranium you find in some stores labeled as a "mosquito plant." Those may smell like citronella but are about as close to citronella as the lime-scented geranium is to a lime tree. Citronella is a clumping grass that grows five to six feet tall. The coarse, grasslike leaves are gray-green and aromatic and are borne on cane-like stems. Other names for citronella are Nardus or Nard grass.
Citronella is generally purchased as a small plant. Make sure you are getting true citronella, Cybopogon nardus or Citronella winterianus, and not one of the other plants that are sold in catalogs that use terms like citronella-scented. If you live in Zone 10 or below you can probably grow citronella in the garden. It can be used as you would use other ornamental grasses in mixed borders or placed in the herb bed. It does not spread by runners . Propagation is done by splitting large clumps into several smaller ones. It is quite tall when mature, and rather coarse-looking, so place it in the back of the garden. In the North citronella can be grown in a large tub and moved inside to a cool but frost-proof place for the winter. Citronella is undemanding in its care. It should be grown in full sun and watered when it gets dry. It does not like to be too wet, so use care when watering potted plants. A little fertilizer high in nitrogen twice a year in the South, and when you move it back outside in the North, will keep citronella growing vigorously.
The dried or fresh leaves of the citronella plant are treated by steam distillation and yield yellow oil with a pleasant, fresh, lemony-green smell. The oil is used in perfume, cosmetics and in herbal preparations. It is used as a stimulant and massage oil. Citronella oil is said to repel cats as well as insects. The oil also has antiseptic properties and is sometimes used to clean countertops and sinks.
You could plant citronella in areas where you sit to repel insects, or scatter leaves from the plant around you, but there is no scientific research that shows this works. If you want to use citronella for repelling insects, buy pure citronella essential oil from a health food store, green pharmacy or herbalist. Citronella works best as a mosquito repellant when citronella essential oil is mixed with some other carrier oil, such as baby oil, olive oil, etc., and applied to the skin. You may need to experiment to find the right mix that works for you, but start with a few drops of essential oil to an ounce of carrier oil.
The citronella you find in department stores in big bottles for burning as lamp oil is useless, as are most candles and other scented citronella devices, for repelling mosquitoes. Some of them have little or no actual citronella oil. Research has shown that burning even pure essential oil in candles or lamps does little good as an insect repellant.
Never apply pure essential citronella oil directly to the skin. It will cause skin irritation. Even diluted oil may irritate sensitive skin. Try it on a small area first. Some people may have allergic reactions when treated skin is exposed to the sun. Citronella plants may also cause skin irritation when handled. Pregnant women should not use citronella oil; there are some reports that it may harm the unborn child. Some people experience an increased heart rate when using citronella oil and should not use it. Do not take citronella oil internally.
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