Many gardeners decide to add citronella to the garden to keep those swarms of pesky mosquitoes at bay—but there’s more than one plant out there that’s sold under the name of citronella. How do you know which plant is the right one? And how effective are these plants at deterring mosquitoes in the first place? We’ve sorted all this out for you and explained the differences between citronella plant and citronella grass, as well as how well these plants repel mosquitoes, in the article below.
CITRONELLA GERANIUM VERSUS CITRONELLA GRASS AND LEMON GRASS: BOTANY
Citronella geranium and citronella grass are two different species. The botanical name of citronella geranium is Pelargonium ‘Citronella,’ while the botanical name for citronella grass is Cymbopogon nardus or Cymbopogon winterianus.
Citronella grass is a perennial grass in USDA Hardiness Zones 10 through 12, though in colder zones it is often grown as an annual.
Citronella grass is sometimes referred to in common speech as lemon grass, but be aware that although it is in the same family of Cymbopogon plants, citronella grass (Cymbopogon nardus or Cymbopogon winterianum) is a different plant than lemongrass, which has the botanical name Cymbopogon citratus. The only one of these two plants that is mosquito repellent is citronella grass. Cymbopogon citratus, though it visually resembles Cymbopogon nardus, is not a mosquito repellent.
Nurseries and garden centers may sell plants other than citronella geranium or citronella grass under the name of citronella. This usually is done because the plant has a scent similar to the true citronella varieties. These plants are not normally effective in repelling mosquitoes.
CITRONELLA GERANIUM VERSUS CITRONELLA GRASS: APPEARANCE
Citronella grass grows in clumps and can reach relatively large sizes, measuring up to six feet tall and spreading four feet wide when mature. It has tall, narrow lance-shaped foliage that looks like blades of grass.
Citronella geranium has feathery, ruffly, lace-like foliage made up of leaves that spread out with a crinkled, serrated texture. Unlike citronella grass, citronella geranium produces flowers. The flowers of the citronella geranium may be pink, purple, or white.
You can tell citronella plant and Cymbopogon citratus apart because the lemon grass Cymbopogon variety has completely green foliage, while citronella grass has a red tint to the pseudostems (the part of the plant that looks like a stem but is in fact made from the overlapped bases of the leaves).
CITRONELLA GERANIUM VERSUS CITRONELLA GRASS: REPELLING MOSQUITOES
Citronella grass is known for being repellent to mosquitoes, but it is the oil of the plant that does the repelling, so simply growing the grass in your garden will not discourage mosquitoes from the area.
Studies are actually contradictory as to whether the oil of citronella grass is effective against mosquitoes. Some studies have shown the oil of citronella grass to effectively repel mosquitoes, but other studies did not show the oil to have any repellent properties. For this reason, the European Union has ruled that citronella grass cannot be sold or advertised as an insecticide.
Despite its name, studies have shown that citronella geranium does not effectively repel mosquitoes.
Now that you know all the various plants that can be sold using the name “citronella,” you also know that none of these plants will deter mosquitoes simply by being present in the garden. However, you can create mosquito-repellent products using the oil from the citronella grass plant. You can learn more about plants with mosquito-repellent properties in our articles Repel Mosquitoes by Growing These Plants and How to Repel Mosquitoes with Container Plants.