Is it your position then that the exact measurements of water, light and nutrients for each plant would ensure that each plant will always flower and yield to fruition? Say that to any farmer, and they'll tell you the variables are far more complex, otherwise every plant in every field will yield under normal conditions.

[ but that is interesting. as the onion peels apart in his hands: ] Even if the onion were to grow, though, I just realised - not all plants would work. If there aren't insects, there are no pollinators.