The oil from a citronella plant does have mosquito-repelling properties. But the plant itself doesn't do much to keep bugs away.
To keep mosquitoes from crashing your summer evenings, you might be tempted to try anything to put these biting bugs back in their place. A citronella plant (sometimes even labeled as a mosquito plant) might seem to offer a simple, sustainable solution among all the repellent sprays, torches, and gadgets. You might see claims that simply planting it will encourage mosquitoes to go elsewhere. Other sales pitches suggest that if you rub the leaves on your skin, the scent will act as an all-natural alternative to sprays. But does a citronella plant really repel mosquitoes, or is this just marketing hype? Here's what you should know before growing and using a citronella plant as a bug repellent.
What is a citronella plant?
Citronella plant is a marketing name for a variety of scented geranium that contains citronellal, the chemical bugs don't like (it's also responsible for the plant's distinctive lemony scent). You may also see this scented geranium sold under names like citrosa mosquito fighter or mosquito plant. Its botanical name is Pelargonium x citrosum 'Van Leenii', and like other scented geraniums, it's a tender perennial. Be aware that some sellers use the name citronella plant for other types of scented geraniums that have no citronellal. Check the nursery tags or website description to make sure you're actually getting the variety called 'Van Leenii'. It's also sometimes referred to as 'Citrosa' or 'Citranium'.
Does a citronella plant repel mosquitos?
In a lab setting, citronellal has been found to repel bugs. They detect the vapor and avoid it. That's why this chemical is the star ingredient in popular citronella oil products such as candles, torches, bracelets, and sprays. But citronella plant doesn't actually contain much citronellal—its essential oil contains less then 0.1 percent of it. The sources for commercial citronella products are actually two tropical lemongrass species. Their oils contain at least 10 to 20 percent citronellal.
In light of these facts, let's look at the two claims commonly made about citronella plants. The first is easy to dismiss. Simply having a citronella plant in your garden won't deter mosquitoes. Some gardeners swear that it works, but studies have found that it doesn't. Even if you plant a whole garden full of citronella plants, it still won't be enough to have a repellant effect on mosquitoes.
The second claim about rubbing the leaves on your skin is a little less straightforward. On the one hand, it's true that citronellal can act as a repellent. But the crushed leaves of citronella plant still don't give you much benefit over going out repellent-free. When you consider that studies usually even slam more potent, advanced citronella products as poor performers, it quickly becomes clear that using your scented geranium to keep away mosquitoes isn't effective. Even the CDC snubs citronella products. As if this weren't enough of a citronella diss track already, one study showed that Victoria's Secret Bombshell perfume outperformed some citronella-based products.
If you still want to experiment with citronella plant as a mosquito repellent, keep in mind that citronella can irritate skin and cause rashes. You'll also need to coat not only your exposed skin, but your clothing—unless you have a mosquito-proof outfit. And then you may need to reapply it as frequently as every 20 minutes. You'd need lots of citronella plants around to have enough leaves to apply just an evening's worth of repellent.
To source a repellent from your garden, you'd be better off trying another plant with more citronellal in the leaves. Along with the previously mentioned lemongrass, lemon balm can contain nearly 40 percent and kaffir lime leaves contain about 80 percent. And there is another scented geranium called 'Dr. Livingstone' that contains 9 percent.
Growing Citronella Plant for Fragrance
Although citronella plant doesn't do much to repel mosquitoes, it's still well worth growing. It's often a gateway plant to the world of scented geraniums. Growing a collection of scented geraniums allows you to experience a palette of delicious fragrances. Besides citronella, these plants can smell like orange, strawberry, rose, nutmeg, coconut, ginger, mint, and many other fruits, spices, and flowers. They're a must-have for lovers of fragrant plants.
Unless you live in USDA Zone 9 or warmer, a citronella plant is best grown as an annual. Or you can bring it inside for the winter and grow it as a houseplant in the sunniest window you can give it. Under ideal conditions, it will develop dainty pink flowers, but its main value is in its fragrant leaves. You can rub them in the middle of winter and feel like you're in a summer garden again. After the risk of frost is over in spring, move your scented geranium outdoors where it's more likely to flourish. Bring it back in when there's a threat of frost in fall.
Some gardeners have success growing scented geraniums like citronella plant outdoors right next to a building foundation all the way down to Zone 6. But before trying your luck, you may want to root cuttings of your geranium in case the main plant dies outdoors during winter.