Mentha x piperita, commonly known as the peppermint plant, is a perennial that requires little care in temperate climates but will spread quickly if not combined. A naturally occurring hybrid cross of spearmint and watermint, the peppermint plant propagates via rooting and is best grown within a container or confined space. This herb thrives in partial shade or full sun in a rich soil that retains water.
It is not possible to grow a peppermint plant from seed, as its seeds are typically sterile, so the proper method of propagation is to use cuttings from a healthy plant. In summer, cut several 3 inch (7.62 cm) lengths of stem, selecting from new growth that is not yet stiff with age. Bury each cutting in potting soil that has been watered and drained 24 hours ahead of time, and then water again after planting the cuttings. Keep the pot in a brightly lit area that stays at 50 degrees F (10 degrees C) or higher, but do not place the pot in direct sunlight. Allow the cuttings to root and begin growing before watering again.
A peppermint plant should be transplanted into an area where it can spread without interfering with the growth of other plants. Alternatively, use a container that is at least 12 inches (30 cm) wide, burying the container below ground to the rim in order to impede the peppermint's spread. In areas with cold weather, mulching the peppermint plant will help it return year after year. Most species will grow to be up to 3 feet (0.9 m) high. Cultivars of the peppermint plant include chocolate mint, white peppermint, eau de cologne mint, and black peppermint.
For use of the fresh or dried peppermint herb, harvest the stems during the summer as the plant grows. This is best done during morning hours before the peppermint plant blooms, when the oil content is said to be highest. The plant will produce small purple or white flowers, typically in July or August.
The peppermint plant is valued for its aromatic oil, which has been used medicinally since the ancient Egyptian era. In modern times, peppermint is used commercially to flavor items such as ice cream, toothpaste, tea, and candies. Peppermint oil or tincture is known as a folk remedy for a variety of physical complaints. Some people use it internally or topically to treat gastrointestinal distress, headaches, skin problems, and cold symptoms. Peppermint is believed to have antifungal, antiviral, and antibacterial properties.