Skip to main content

Posts tagged: Essential Oil Testing

In this experiment, I tested thirteen different essential oil blends which are marketed as being protective against bacteria, viruses, and fungi. I tested each for their ability to inhibit the growth of bacteria in an in vitro bacteriological test using petri dishes. My intentions for this experiment are (1) to determine if these blends actually inhibit the growth of bacteria as claimed, (2) to see which brands are most or least effective and to compare efficacy, and (3) to see what can be learned about which essential oils in the blends tested may contribute to increased efficacy against bacterial growth.

Brands Tested.

Nature's Gift, Butterfly Express, Edens Garden, Veriditas Botanicals, Ameo, Young Living, Plant Therapy, Plant Therapy KidSafe, Aura Cacia, doTERRA, Healing Solutions, Fabulous Frannie, and Native American Nutritionals (NAN/RMO).


This experiment is different from the previous lemongrass experiments due to the fact that each brand has their own immune defense formula and contains several different essential oils. While most brands tested contain essential oils of clove, cinnamon, lemon, rosemary, and eucalyptus, some brands have chosen to depart from this formula.

Nature's Gift: Lemon Myrtle, Tea Tree, Cinnamon Bark, Cassia, Cedarwood, Pine, Lemon Eucalyptus, Ravensara, Lemon Tea Tree, Clove.

Butterfly Express: Cinnamon Bark, Clove, Eucalyptus globulus, Lemon, Lemon Myrtle, Oregano, Oregano Wild, Rosemary, Thyme.

Edens Garden: Clove, Cinnamon Leaf, Rosemary, Lemon, Eucalyptus.

Veriditas Botanicals: Cinnamon Bark, Clove, Lemon, Eucalptus radiata, Rosemary Cineol.

Ameo: Clove, Cinnamon Bark, Lemongrass, Orange, Lemon, Rosemary, Eucalyptus radiata.

Young Living: Clove, Lemon, Cinnamon Bark, Eucalyptus radiata, Rosemary.

Plant Therapy: Lemon, Clove, Eucalyptus, Cinnamon Cassia, Rosemary.

Plant Therapy KidSafe: Spruce, Marjoram, Lavender, Rosalina, Lemon.

Aura Cacia: Sweet Orange, Lavender, Lemon, Red Thyme, Tea Tree, Eucalyptus globulus, Rosemary.

doTERRA: Wild Orange, Clove, Cinnamon Bark, Eucalyptus, Rosemary.

Healing Solutions: Cinnamon, Clove, Eucalyptus, Lemon, Rosemary.

Fabulous Frannie: Clove, Lemon, Rosemary, Cinnamon, Eucalyptus.

Native American Nutritionals: Clove, Cinnamon Bark, Lemon, Lemon Eucalyptus, Ajowan Seed, Thyme, Orange, Oregano, Nutmeg, Rosemary, Red Mandarin, Ginger Root.

For methods, please check the "About Me" section.

Observations & Results.

In a layout arbitrarily chosen by myself in an attempt to order them from least effective to most effective based on initial observations, here are the results after 48 hours incubation:

Below, blends were grouped based on the size of the zone of inhibition around the oil (measuring the radius from where the essential oil blend was placed on the petri dish). Blends in Group One had a zone of inhibition that was less than 0.5cm. Blends in Group Two had a zone of inhibition that was equal to 0.5cm. Group Three blends had a much larger zone of inhibition, greater than 0.5cm:

Table 1. Scores assigned to groups based on the size of the zone of inhibition.

Below is a larger image of Aura Cacia's "Medieval Mix". This blend, as well as Plant Therapy's KidSafe blend, had a zone of inhibition that did not extend beyond the spread of the oil in the dish (less than 0.5cm).

Below: Plant Therapy KidSafe blend, "Germ Destroyer". The spread of the oil is visible in this image, and bacterial growth occurred just beyond the outer edge of the oil.

Blends were then grouped according to the spatial distribution of bacterial growth. Blends in Group One were defined as having uniform bacterial growth beyond the zone of inhibition. Blends in Group Two had high density spatial distribution. Group Three - medium density. Group Four - low density. And Group Five - sparse.

Table 2. Scores assigned to groups based on the spatial distribution of bacterial growth.

Another distinguishing characteristic between the plates was the amount of large colonies that grew. The image below displays how they were grouped. Group One was defined as having over three large colonies. Blends in Group Two grew 2-3 large colonies. Group Three - one large colony. Group Four - no large colonies.

Table 3. Scores assigned to groups based on the amount of large colonies present in each dish.

One last quality that was considered was the total amount of bacterial growth that occurred in each dish. An image for this was not taken. Scores were assigned as below:

Table 4. Assigned scores for number or amount of colonies/bacterial growth.

The table below displays the assigned scores for each blend according to each distinguishing characteristic observed or measured. Qualities determined to be less effective were given larger marks against efficacy, and therefore higher scores. Scores for each blend were totaled and rank was given based on overall efficacy of the blend. Nature's Gift ranks at the top as most effective and Veriditas Botanicals ranks at the bottom as least effective.

Table 5. A comparison of the essential oils in each blend.


The results of this experiment warranted a much more complex analysis than the previous lemongrass experiments. There were several distinguishing characteristics of the type, spread, and amount of bacterial growth present in each dish. Though some brands clearly performed better than others, there were some that proved difficult to place. For example, Young Living performed well when spatial distribution and total bacterial growth were considered, but ultimately, the size of the zone of inhibition around the oil was smaller than those with higher ranking.

In an attempt to even out the scoring and weight the scores amongst the distinguishing characteristics observed and measured, scores were given from 0-7. You might notice that the zone of inhibition scores were given slightly more weight than the others. This is because I considered this measurement to be of more importance, due to the fact that the zone of inhibition is typically the standard measure used in bacteriological testing.

The justification behind factoring in the spatial distribution of the bacterial growth was to account for the aromatic activity of the blends. It appears that some blends were more effective through aromatic influence than through having a more localized zone of inhibition effect (compare Young Living or Plant Therapy's KidSafe blend which has better scores in spatial distribution, to Fabulous Frannie or Healing Solutions' Health Shield Blend). Since essential oils are valuable for their aromatic action, this is an important quality to consider.

One potential source of error in this experiment is that I only had twelve identical droppers instead of thirteen. I chose to use a different dropper for the Plant Therapy KidSafe blend since Plant Therapy was already being tested. It's doubtful that this had an effect on the experiment however, because the size of the mouth of the dropper is nearly identical to the other twelve.

Another major factor that influences the results of this experiment are that the scores and rankings are based on my observations and measurements, and are ultimately based on my personal judgment. Not everyone will agree on how to score or rank the efficacy of these blends. As an aside, it's more difficult to see clearly in the images each petri dish and the bacterial growth it contains, and therefore some images presented do not accurately reflect what can be observed in person.


Nature's Gift, Butterfly Express, and Plant Therapy are the clear winners amongst the protective blends tested. The main reason for this is likely because each of these departs somewhat from the typical Thieves-like blend. Nature's Gift contains ten different essential oils as opposed to the usual five, and it appears that the additional oils have been chosen wisely. Upon first observation, it might be suggested that Butterfly express performed well because it contains oregano essential oil, which is a known powerful antibacterial. Yet the Native American Nutritionals blend also contains oregano, as well as all of the essential oils listed in the Butterfly Express blend - except for lemon myrtle. Both Butterfly Express and Nature's Gift contain lemon myrtle, which according to the Nature's Gift website, "is a much more effective germ killer than the more familiar Tea Tree". None of the others contain lemon myrtle and therefore it's likely that this oil helped both of these blends claim top spots in the ranking order.

Plant Therapy comes in third (or tied with Young Living) even though its formulation wasn't much different than the typical protective blend. The unique difference from other 5-oil protective blends is that it contains cinnamon cassia instead of cinnamon bark. Both Nature's Gift and Plant Therapy blends contain cassia. Considering the fact that this is the one essential oil that sets Plant Therapy's blend apart from Young Living, Edens Garden, Healing Solutions, Fabulous Frannie, and Veriditas Botanicals, cassia may be the major factor involved in the success of this blend.

Ultimately, it appears that all of the blends tested were able to inhibit the growth of bacteria in the incubator for up to 48 hours. However, Aura Cacia's Medieval Mix and Plant Therapy's KidSafe blend would only be effective topically at 48 hours, but most protective blends are not advised to be used topically because of the skin irritating and sensitizing properties of certain oils. It's nice to note that the rest of the blends were still acting aromatically and inhibiting the growth of bacteria at 48 hours.

Extra Fungus/Mold Experiment.

If you've read through this post, you get to see the additional experiment I performed with these blends, on some mold I discovered growing on my organic strawberries. I almost threw them out, but then took the opportunity to put these protective blends to the test for their anti-fungal activity. The only problem was that I was one petri dish short. So there's no control to compare the blends to. Oops.

Hop onto my Facebook page and let me know what you think! Thanks for reading!

Twitter Facebook Pinterest LinkedIn

A conclusion on comparing several brands of lemongrass, including Jade Bloom lemongrass.

Please read the post on the original lemongrass experiment, here. The second lemongrass experiment is here.

Brands Tested.

Young Living, doTERRA, Aura Cacia, Plant Therapy, Edens Garden, Jade Bloom, Native American Nutritionals/Rocky Mountain Oils, Now, and Mountain Rose Herbs (not pictured).

All brands of lemongrass are of the variety Cymbopogon flexuosus, except for NAN/RMO, which is Cymbopogon citratus.


For this experiment, I used separate identical glass droppers to account for the varying size in droppers that came with each brand's bottle of essential oil. The petri dishes were examined at 24 hrs incubation to observe preliminary results. At 48 hrs the petri dishes were removed and images were taken. For additional explanation of methods, please check the "About Me" section.

Observations & Results.

Order from least inhibition to most (based on my personal observation and examination of the Petri dishes): NAN/RMO (top right), (from left to right) Edens Garden, Jade Bloom, Plant Therapy, Aura Cacia, (bottom left to right) MRH, Young Living, Now, and doTERRA.

Results from the original lemongrass experiment:
NAN/RMO, Now, Plant Therapy, Aura Cacia, doTERRA, Young Living, MRH, Edens Garden.

Results from the second lemongrass experiment:

NAN/RMO, Now, Edens Garden, Plant Therapy, Young Living, doTERRA, Aura Cacia, MRH.

Table 1: Analysis of results from all three experiments.

Table 2: Adjusted results based on modifying outliers.


The third lemongrass experiment includes Jade Bloom lemongrass. A friend and follower of the blog shipped me a new bottle in order to test it against the others. It appears to have performed as well as several of the other brands tested.

Less bacteria colonies grew in this experiment overall, which may be due to the sudden drop in temperatures in my region. Each brand inhibited bacterial growth, except that NAN/RMO had a bacteria colony grow on the location that the essential oil was placed, for a second time (see Part 2). However, halfway through the experiment at 24 hrs incubation, the bacteria colony was not yet present. Therefore, NAN/RMO lemongrass inhibited bacterial growth locally at 24 hrs, but not at 48 hrs. A few other observations to note are that Edens Garden lemongrass performed similarly to how it did in the second experiment, Now lemongrass performed much better than in the first two experiments (relative to the other brands), and the rest remained fairly consistent.

In combining the three experiments, the brands were ranked based on relative efficacy and totaled the scores. (See Table 1.) Those with the highest totals were consistently less effective and those with the lowest were consistently more effective. In order to account for the outliers in the experiments, specifically the results for Edens Garden in the first experiment and Now in the third, I adjusted the ranking score to what would be comparable for each brand in the remaining experiments. (See Table 2. Note: This part of the analysis may not be statistically sound, because many more experiments would have to be done in order to determine true outliers, but I believe it to be a reasonable adjustment to make in order to rank the effectiveness of each oil across the three experiments.) Mountain Rose Herbs performed consistently better than the other brands, as well as doTERRA and Young Living. Aura Cacia follows closely behind, then Plant Therapy, Edens Garden, Now, and finally NAN/RMO as least effective.


Combining the results from three separate experiments is more valuable than results from one or two. This is why studies are repeated and even a reason why the accepted scientific conclusions on one subject may change over time. Ultimately, every oil tested was found to inhibit bacterial growth in the experiments, to a greater or lesser extent. Even NAN/RMO lemongrass fully inhibited bacterial growth in the first experiment, and inhibited bacterial growth at 24 hrs incubation in the third. The fact that NAN/RMO lemongrass was a different variety than the others may be the reason for it's reduced effectiveness and/or longevity in comparison to the other brands. The analysis on the three experiments can be scrutinized and the execution of the methods debated, but the results are here for you to make your own conclusions as well. In the future, I would like to see how lesser-known brands of essential oils stack up against these popular brands.

Twitter Facebook Pinterest LinkedIn

This is why you repeat experiments...
Please read the post on the original lemongrass experiment, here.

Brands Tested.

Now, Edens Garden, Aura Cacia, doTERRA, Young Living, Plant Therapy, Native American Nutritionals/Rocky Mountain Oils, and Mountain Rose Herbs (not pictured).

All brands of lemongrass are of the variety Cymbopogon flexuosus, except for NAN, which is Cymbopogon citratus.


For this experiment, I used separate identical glass droppers to account for the varying size in droppers that came with each brand's bottle of essential oil. For additional explanation of methods, please check the "About Me" section.

Observations & Results.

Results from the original lemongrass experiment:

Here's the Native American Nutritionals (Rocky Mountain Oils) dish. It appears that one bacteria colony grew directly on the spot where I placed the drop of lemongrass.


The second lemongrass experiment is interesting to see. Certain brands performed better, others worse, and some were consistent with respect to the first experiment. Of note, it appears that all oils exhibited more aromatic influence throughout each dish, rather than inhibiting bacteria mostly within a certain zone closest to the drop of essential oil. It's possible that the incubator held a slightly warmer temperature than for the previous experiment, vaporizing more of each oil. Edens Garden lemongrass did not outperform the others this time, most likely because of the change to using identical glass droppers. Native American Nutritionals (NAN) seemed to inhibit some bacterial growth in this experiment, if only through aromatic influence on other areas of the dish (compare control to NAN dish), and in both experiments, NAN inhibited bacteria the least of all brands tested. This might be because of the variety of lemongrass (Cymbopogon citratus). It is disappointing that in this experiment, the NAN lemongrass dish did not have a zone of inhibition directly where the essential oil was placed, and I'm not sure what would account for that. The Now brand lemongrass was next in line for a second time. Edens Garden dropped to third-most effective, and Plant Therapy bumped up one. Young Living and doTERRA pretty much maintained their positions, and Aura Cacia outperformed them this time. Mountain Rose Herbs lemongrass also continued to be effective at inhibiting bacterial growth.


Repeating experiments is important. Due to human error and experimental design flaws, among other factors, performing one experiment will only tell part of the story. With this second experiment, we are able to get a clearer picture of how effective one brand of lemongrass essential oil is, relative to the others. I'm even tempted to do a third...

Twitter Facebook Pinterest LinkedIn

In this first experiment, I tested lemongrass essential oil for its ability to inhibit bacterial growth. The aim was to create an experiment comparing several brands of lemongrass to observe the potential differences in the amount of bacterial inhibition by each product.

The Science.

Antibacterial and antifungal activity of ten essential oils in vitro. "Lemongrass, eucalyptus, peppermint and orange oils were effective against all the 22 bacterial strains... All twelve fungi were inhibited by [lemongrass and six other essential oils]."

Brands Tested.

Now, Edens Garden, Aura Cacia, doTERRA, Young Living, Plant Therapy, Native American Nutritionals/Rocky Mountain Oils, and Mountain Rose Herbs (not pictured).

All brands of lemongrass are of the variety Cymbopogon flexuosus, except for NAN, which is Cymbopogon citratus.

For methods, please check the "About Me" section.

Observations & Results.

Two different types of bacteria colonies grew on the plates. This is observed most clearly in the control. In the test group, both types of bacteria were inhibited from growing in each plate. The degree of inhibition and number of colonies that grew varied slightly, depending on the oil. All brands of lemongrass inhibited bacterial growth.


One potential flaw in this experiment is that the amount of essential oil tested may have not been as consistent as intended. Though one drop of oil was used for each test, the existing droppers from each brand's bottle produces a different amount of oil in each drop due to the varying size of the dropper. To a lesser extent, viscosity of each oil may also be a factor. In future experiments, existing droppers will be removed and individual identical glass droppers for each oil will be used.

Lemongrass essential oil has several uses, and is effective for other applications - it's not just an antibacterial. For example, it has been found in one study to have potential anticancer activity. I have personally used it to help heal a ganglion cyst in my wrist and I enjoy diffusing it when I'm feeling like disinfecting the air in my home. Want to learn more? Head to Pub Med and search for studies involving lemongrass.


I call this a win for all brands of lemongrass and essential oils in general. You can see that some oils inhibited the growth of bacteria a bit more than others. In one dish, it appears that the oil inhibited one type of bacteria entirely. In some, it appears that the aromatic action of the oil helped to increase the amount of inhibition. Ultimately, all of the oils prevented the growth of bacteria.

Twitter Facebook Pinterest LinkedIn