Most of us are familiar with the grassy, lemony aroma of citronella oil — we've smelled it in scented patio sprays and outdoor candles. The oil is steam distilled from the leaves of a tropical grass.
There are two distinct types of citronella grass, which are sometimes labeled as different species: Cymbopogon nardus, known as lenabatu or Ceylon type citronella, and C. winterianus known as maha pengiri or Java type citronella. The Ceylon type is the original cultivated variety. It grows on the island of Sri Lanka and may have arisen as a distinct form of yet another type of wild grass called C. confertiflorus. The Java type, C. winterianus may have arisen as a distinct form of the Ceylon type, C. nardus.
Until the early part of this century, the Ceylon type citronella was the most widely produced citronella oil. Gradually the Java type has come to dominate the market due to its higher yield of oil. It's grown commercially on a worldwide scale in places like Haiti, Central America, the South Pacific and tropical Africa.
Citronella's main constituents are citronellal and geraniol. Together they produce a rosy-floral, lemony aroma. A mixture of minor constituents including camphene (camphor-like), borneol (chamomile-like) and methyleugenol (clove-like) combine to produce a peculiar aroma resembling damp, musty vegetation. This secondary aroma characteristic is more prominent in the original Ceylon type than in the Java type. Before the advent of chemical sprays, Ceylon citronella was used in combination with Virginian red cedarwood oil in commercial insect repellents. Because of this original use, some people still insist on the Ceylon type for keeping insects at bay. Bugs like gnats and mosquitoes probably don't make that distinction; their aversion is to the citronellal, constituent which is found in both types of oil. Citronellal is actually present at higher levels in the Java type.
The Java type of citronella oil is one of the most widely used perfumery oils. Because of its high citronellal content (up to 50% of the total volume), and geraniol (up to 45% of the total volume), it's often used as a starting point for perfume materials which are isolated or fractionated from the oil. Fractionation is a process in which the oil is redistilled in a vacuum, so individual constituents, or fractions, are separated out as they evaporate one after the other. This is possible because each constituent has its own rate of volatility based on time and temperature. It's much easier for a perfume maker to create unique aromas by combining individual, clean fractions as building blocks than it is to combine whole oils with their complex mixtures of constituents. Citronellal and geraniol are two of the most important and widely used perfume building blocks. Nowhere else do they occur together in such large amounts as they do in the Java type citronella oil.
Using Citronella at Home
Because of its association with insect repellency, citronella is usually overlooked as an aromatherapy oil. That's a shame because citronella possesses warming and activating qualities on both the physical and mental levels.
Physically, citronella will produce a subtle sensation of warmth when properly diluted in a massage oil and applied to the skin. Dilute 3 drops of essential oil per teaspoon of massage oil. Using this in a friction massage may help bring relief to painful joints and muscles. Perform a simple friction massage by rubbing a targeted area vigorously until warmth is produced by the friction. The idea is to bring blood and soothing warmth into the affected area. Combine citronella with eucalyptus to heighten this effect, or use lavender to make the effect more moderate and balancing.
Like its closely related counterpart, essential oil lemongrass, citronella is astringent and can help with oily complexions. First, test a single drop of oil on your inner arm to make sure that it won't irritate your skin. Then apply no more than two or three drops to a soft cotton ball to gently wipe clean any oily areas. Follow this with your regular cleaning and moisturizing routine.
On a mental level the aroma of citronella can be gently clarifying. Combining citronella with lemon will support its clarifying benefit while the addition of geranium or rose will make it more moderate and balancing. People who object to the aroma of citronella can easily modify its damp-musty undertone with a few drops of rose otto.