You could look at this another way though. If you wanted to test this heresy against materialistic understandings, what better way than to test it on plants to avoid the placebo effect and to have it tested on two plant varieties over two seasons against water controls and against the industry standard chemical and then compare results as measured and collected by the industry bodies who test preparations of whatever provenance. And should this come up with the uncomfortable result that it does seem to be effective what would you think of a scientist whose reaction was - no I won't bother with this? I would think it would be due diligence to bother quite a lot with this because if everyone has done the job they are trained to do, it is important.
Bentospawn/Psychonaut, if you would like to really explore this there is a paper called "Homeopathy for Plants - Yeah Right" to which google will no doubt direct you in which the reasoning you have brought here is explored in great detail in relation to the research I mentioned. It covers the ground so perhaps we don't have to do the cartography in full again here.