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.

Methods.

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.

Comments.

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.

Conclusions.

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...