Citronella plant: the myth
No one likes being bitten by a mosquito. Wouldn’t it be great if you could have dinner on the back patio without being eaten alive? Why not just put a citronella plant on the table? Give it a try, but sorry to say, it will not work. First, it is the wrong plant. Second, in order for a plant’s essential oils to repel insects they must be released through crushing or distillation.
The on-line and box stores sell a plant called citronella which is a citronella-scented geranium, Pelargonium graveolens ‘Citronella’. While this plant does contain minute amounts of citronella essential oil, it is not releasing the essential oils into the surrounding air to repel those pesky mosquitos.
If the leaves are crushed and rubbed onto the skin, it may repel mosquitos for a millisecond. The plant was supposedly introduced by Dutch scientist, Dirk Van Leeni, in the 1980’s. He claimed to have bread rose scented geranium (Pelargonium graveolens) with lemon grass (Cymbopogon). Later testing proved this to be false.
While citronella-scented geranium will not keep your evening outdoor meal free from buzzing insects, it is a wonderful plant to grow. Fragrant, deeply lobed leaves are topped by clusters of lavender-pink flowers all summer. It can reach 2-3’ in a single season with a minimum of six hours of direct sun. Fantastic in containers.
It can survive brief periods of freezing temperatures (zones 8-11). All scented geraniums are extremely easy to overwinter indoors. The flowers are edible and the leaves can be used in teas or flavoring culinary treats. Portland Nursery carries this variety and many other varieties of scented geraniums.
To continue the quest to find a mosquito repelling plant we turn to lemon grass, Cymbopogon. This is plant soaked in deep history, with many layers to unravel. Lemongrass was used medicinally by the many cultures throughout history. Ailments range from fever relief to stomach easing.
There are 56 species found tropical Asia and Africa, so which one is the source of citronella? Bottles of essential oil reveal Cymbopogon nardus is the primary species used in the industry. This African species contains high amounts of citral (lemon scent). Unfortunately, we do not carry this species at Portland Nursery.
West Indian lemongrass, Cymbopogon citratus, is also commonly distilled into essential oil. It not only can help repel mosquitoes, but also help a bee keeper attract a swarm of honey bees. The leaves must be crushed and rubbed on the skin or extracted to be effective. Fresh and dried leaves are also wonderful in tea and essential for many culinary dishes. This species grows enlarged leaf bases which are prized in Thai and Vietnamese dishes. It is wonderful in containers or planted in ground. Lemon grass grows up to 4’ tall and 2-3’ wide in full sun. It requires good drainage, and is drought tolerant. Hardy in zone 9, and requiring indoor winter protection in Portland and surrounding areas. This species can be found at Portland Nursery.
East Indian lemongrass, Cymbopogon flexuosus, is the source of lemongrass oil used to flavor food and cosmetics. The fresh leaves are splendid in teas, potpourris and culinary flavorings. This species does not form a swollen stem. It grows 4-6’ tall and 24-36” wide in full sun. Cold hardy in zones 9-11, requiring winter protection in Portland. This species can be found at Portland Nursery.
There are a variety of other plants with essential oils that will repel mosquitoes when crushed and rubbed on the skin, or extracted.
Some of these plants include: rosemary, lavender, catnip, eucalyptus, garlic and mint. The easiest way to make your own bug repellant is by using store bought essential oils.
A tincture made from your homegrown herbs can also be effective. A tincture is an extract of plant material using alcohol, such as vodka.
Grapeseed oil (or other light weight oils) can also be infused with lemongrass and other mosquito repelling herbs to create a pleasant, somewhat effective repellant. Lastly, a strong tea made with herbs may be mildly effective.