Mint comes in many varieties, from the well-known peppermint and spearmint to exotic chocolate or pineapple mint. Mint is one of the easiest plants in the garden to propagate and can be done several different ways. In fact, it's so easy to propagate mint that it sometimes propagates itself and spreads like wildfire.
Take stem cuttings. Cut four to six inch pieces with three sets of leaves. Remove the bottom set of leaves. Insert the cutting into an individual 2-inch pot filled with potting soil or builder's sand. Cover each pot with a clear glass or plastic jar placed upside down, making an individual greenhouse. Set into deep shade and roots will form in three to six weeks
Take root cuttings. The roots travel just under the surface of the soil, sending up new shoots every few inches. Cut off 2- to 4-inch pieces of the mint's roots. Pot them up in individual 2-inch pots. Put the individual pots into the shade and keep them moist until you notice leaves beginning to grow in two to four weeks. At this point they can be transplanted into the ground where you want them to grow.
Propagate mint by root division. Dig up your mint plant and place it on a hard surface. Use a sharp knife to slice the plant into smaller sections, making sure that each section has some roots and some leaves. Replant the divisions directly into the ground and keep evenly moist until new growth begins.