its _possible_ to do this nickelz but the level of actual taste would be highly suspect, the reason roses and flowers do the coloring thing is because they take up water, thinking its water, but its really water-plus. if you mixed old peppermint into the soil it would only decompose into a natural fertilizer. and watering with a flavoring would probably only cause a placebo effect as the molecules of the "peppermint flavor" would probably be too big or rejected by the roots. your best be would be what Arc sujested, or even mixing in dried peppermint into the final batch, u know like mixed crumbles of dried leaves.
this would be a cool idea if it worked though, but im plausible
