Picture this: You're driving along across the Prairies on a lovely day, admiring the miles of crops spread out around you. Wheatfields in 'amber waves of grain'. Canola in sulfur yellow blossom. And what's that green field coming up? Not corn, or soybean, it's....( duh duh dum) spearmint! And the soft green down the road is dill! Hundreds of acres of mint and dill!
Not seeing where the horror comes in? Mint (and a number of it's relatives) are very good at spreading via runners. On the ground, under the ground...most gardeners who have experience with it either put it away by itself somewhere, or put it in pots. Dill doesn't do the runners, but it reseeds very easily. At my parent's, the dill has not had to be deliberately replanted in years. Mostly the idea is to simply remove it from all but a small fraction of the garden every spring, using the removed plants for fresh dillweed, and let some of the stalks grow for dillseed in the remaining patch. Always, some of the seedheads drop seeds, and we're ready to start over the next year.
Don't worry, I don't think they're taking over the world yet. But these huge field of herbs do exist. I was talking to someone who grows them, they go for things like essential oils - and you know mint is in a lot of things as flavoring! So I suppose if I had ever thought about it, I would have realized that there must be equivalents of the picturesque fields of lavender for other herbs grown for scent and flavor. But quite frankly, the idea of hundreds of acres of mint was novel. And scary. And I shall be remembering it every time I open the toothpaste tube. I raise my toothpaste in a salute to the growers, people brave enough to wrangle and control that green tide of herbs, that we may have flavoring.