A cross between other mints, peppermint plants are sterile and propagate by division or cuttings. A single peppermint plant is capable of parenting an entire garden or flowerbed. Before you take cuttings, select a healthy peppermint plant free of disease and take the cuttings during the summer. Mint is an invasive plant, and if given the opportunity it will take over the entire garden.
Fill the pot with a mixture of equal amounts of peat moss and perlite. Mix well to combine before adding to the pot.
Pinch off a stem from a healthy peppermint plant and remove the leaves from its bottom half.
Cover the cut end of the stem with rooting hormone.
Insert the cut end of the stem into the pot and soil mixture, leaving about 2/3 of the stem above the soil line. Tap the pot gently to set the soil.
Water the plant thoroughly so that the soil is well moistened but not muddy.
Place the bag over the pot to create a greenhouse and set in an area with filtered sun. Keep spoil moist but not muddy.
Remove the plastic bag when new leaf growth appears.
Transplant the plant to the garden after the roots are established.