A few years ago, I grew a lemon eucalyptus plant (Corymbia citriodora). I discovered it at a farmers market in Alexandria, VA, and the seller told me it was from Australia and was not hardy here in Zone 7 so it would have to be brought indoors in the fall. I had not seen one before so I was intrigued. This past weekend I saw them for sale at Greenstreet Gardens in Alexandria although the tag said “lemon bush” (photo to the left).
The lemon eucalyptus plant is great if you want a strong lemon scent for something like potpourri. It is also a medicinal herb; the leaves are used in traditional aboriginal medicine. The essential oil in the leaves is an antiseptic and is used in perfume. The plant is a rich source of citronella which is a mixture of many compounds including citronellol, citronellal and geraniol. The oil of eucalyptus is an effective mosquito deterrent. The plant itself cannot deter mosquitoes so don’t be fooled into thinking that a plant on the patio will keep you bug free.
There is a difference between the essential oil and the oil of eucalyptus. The Centers for Disease Control and Prevention (CDC) has recognized oil of eucalyptus (OLE) as effective in deterring mosquitos. OLE contains p-Methane-3,8-diol (PMD), a naturally occurring compound obtained from the spent distillation of the leaves. PMD also can be synthesized in a laboratory. PMD is the only plant-based mosquito repellent that has been recognized by CDC to be effective in repelling mosquitoes while posing no risk to human health. However, children under the age of three should not use this because it can irritate the eyes. PMD has been registered by the Environmental Protection Agency (EPA) as an effective plant-based mosquito repellent.
Lemon eucalyptus essential oil has a lower level of PMD and is not effective in repelling mosquitoes. The essential oil is made by steam distilling the leaves and twigs.
If you want a commercial, plant-based mosquito repellent, look for a product that lists “oil of lemon eucalyptus” as an active ingredient, which should provide up to six hours of protection.
My lemon eucalyptus plant thrived outside in the summer in a large container in full sun. It grew several feet tall. The lemon scent was so strong, all you had to do was brush the leaves with your hand and you could visualize a bowl full of lemons. Of all my lemon scented herbs — lemon balm, lemon grass, lemon verbena, lemon mint, lemon thyme, and lemon scented geranium – this was the most fragrant.
In its native habit, it would grow to be a tall evergreen tree and bloom tiny white flowers. Here in this area, you would have to bring the plant indoors in the fall to keep it alive. Or you can just purchase another one next year. I am glad to see it in nurseries now and I recommend growing this for its beautiful scent. The foliage should dry well (retain the scent) for potpourri or maybe even for wreaths.
This is the lankiest and most elegant of the genus (both Eucalyptus and Corymbia) in California. It is more popular in Southern California than here, and can actually get damaged by frost where winter weather gets cooler than it does here. Only one specimen inhabits a small portion of one of our landscapes (which includes a few odds and ends for childrens’ ‘outdoor science’ classes). They are really best in groups of a few specimens. Single specimens can look rather scrawny alone. Unfortunately, they grow too tall for their aromatic foliage to be within reach. It can be grown for its foliage rather than as a tree by coppicing it to a stump every few years. The juvenile new foliage is more aromatic than the adult foliage.