lemon eucalyptus plant right after I purchased in beginning of May, before I planted outside
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 about 10 inches high 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. 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.
leaf close up to show bristles
The lemon eucalyptus plant is about 3 feet now and not very bushy. In its native habit, it would grow to be a tall evergreen tree and bloom tiny white flowers. In October, I will bring it indoors so it probably will not get much taller than 4 feet. 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. The plant itself cannot deter mosquitoes so don’t be fooled into thinking that a plant on the patio will keep you bug free.
two months later, plant in larger container
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 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.
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.
This is a common tree in coastal regions of Southern California. It is not quite as common here. We will be planting one at work this autumn. I would like to add a few more, because they look rather silly alone.
The juvenile foliage is more aromatic than smoother adult growth. As your tree gets big enough to develop adult growth, it will likely need to be pruned back aggressively, which should stimulate development of juvenile growth instead. I grow a blue gum (eucalyptus) in my own garden for the aromatic juvenile foliage, and pollard it annually through winter so that it never develops adult growth. The adult growth and bloom is pretty, but not so aromatic. Besides, blue gum is such a horridly aggressive and big tree that I can not allow it to grow as it would do naturally.
Blue gum is the most popular eucalyptus for eucalyptus oil and essential oil of eucalyptus, but is often labeled as generic ‘eucalyptus’. The aroma is very strong, but also very different from that of lemon gum. Eucalyptus oil and essential oil of lemon gum must be labeled as such.
It is interesting to hear from a place that is warmer than here where the plant can survive year round.
Blue gum gives all eucalyptus a bad reputation because it was planted so extensively for wood pulp, and then abandoned. The trees are huge, and drop limbs from very high up. It is unfortunate, since so many other species of eucalyptus are so practical for landscapes.
So happy to read about this plant. Coincidentally, I bought one at Thanksgiving Farm this year and enjoying its beautiful foliage. I’m thinking of using some of the leaves in my step daughter’s bridal bouquet.
That is a good idea. Mine has now grown to be very large and will be great for bouquets.
Thanks for the blog!
I have been researching Ankle Biters from living here in Southern California, because I have been getting bitten so much this summer/fall. Thank you for posting that interesting info regarding the PMD levels and how OLE is effective against mosquitos, while the essential oil has lower pmd levels and isn’t as effective.
I almost went out and bought some essential oil because I didn’t want to buy any of the commercial available mosquito repellants. But after reading your blog, I’m not so sure the essential oil would really help.
You are welcome.
Pingback: Lemon Eucalyptus – The Herb Society of America Blog