by Peggy Riccio
Editor’s Note: This article was originally posted on July 5, 2021 at https://pegplant.com/2021/07/05/lemon-eucalyptus/
A few months ago, I was at a farmer’s market in Alexandria, Virginia, when a particular plant caught my eye. It was a lemon eucalyptus plant (Corymbia citriodora). It was less than a foot tall in a plastic container. I love lemon scented herbs – I think I am subconsciously collecting them. 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 brought it home and placed it in the garden in full sun, where it thrived so well I had to move it to a larger container within a few months. At first, it resented the move but now it is flourishing, still in full sun. It did not even mind the recent heat wave.
The lemon scent is so strong, all you have to do is brush the leaves with your hand and you will 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 is one of the most fragrant. I pulled a leaf off and compared it with the lemon verbena, which I think is the other most pungent lemon herb I have. The lemon eucalyptus leaf was very coarse with small bristles. The scent was strong but more of a musky lemon. The lemon verbena leaf was not as coarse and had an equally pungent lemon scent but was sweet, like sugar and lemons.
The lemon eucalyptus plant is about three feet now and not very bushy. In October, I will bring it indoors so it probably will not get much taller than 4 feet. In its native habitat, it would grow to be a tall evergreen tree and bloom tiny white flowers. I could have planted it in the ground and just let it die with frost but how often does one come across such an unusual plant here in Virginia?
This is not a culinary herb – it is not to be ingested. It is a medicinal herb though; 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, although 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 can also be synthesized in a laboratory. PMD is the only plant-based mosquito repellent that has been recognized by the 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. 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. 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.
When I bought my plant, I wasn’t thinking mosquitoes, I was just thinking it had a pretty lemon scent. Personally, I think I will use the leaves in my potpourri, maybe with a touch of lavender.
Medicinal Disclaimer: It is the policy of The Herb Society of America, Inc. not to advise or recommend herbs for medicinal or health use. This information is intended for educational purposes only and should not be considered as a recommendation or an endorsement of any particular medical or health treatment. Please consult a health care provider before pursuing any herbal treatments.
Photo Credits: All photos courtesy of the author.
Peggy Riccio is the owner of pegplant.com, an online resource for gardening in the Washington, DC, metro area; president of the Potomac Unit, Herb Society of America; regional director of GardenComm, a professional association of garden communicators; and is the blog administrator for the National Garden Clubs, Inc.