Herb Seeds - Peppermint Peppermint is a very common herb that is used in many different types of cooking. It is also believed to be one of the world's oldest medicines. Archaeologists have found evidence to suggest that it was used as a remedy for stomach problems as much as 10,000 years ago Sow peppermint seeds in spring to have plants in the current growing season or in late fall if you want plants first thing the following spring. If you live in the north, it is best to plant pennroyal in the spring. Barely cover the seeds with soil, planting them only 1/8th of an inch deep. Keep your peppermint herbs indoors in the pots to keep them at a manageable size. Plant them outdoors if you wish them to propagate more peppermint plants and grow much larger. They can survive in the poorest of soils once they’ve established themselves, so don’t worry about that. Make sure to plant them well away from any other species that you are trying to grow. They will grow aggressively and kill off any other species of plant in their midst if you allow them to.