Mint, Peppermint (Mentha piperita)
Brandy Mint, Black Mint, Candy Mint
About This Plant
Peppermint gets its name from its pungent, peppery bite and is known for its cool aftertaste that sets it apart from other types of Mints. The “cooling” effect of Peppermint is due to menthol, the major terpene found in its oil. While not used as commonly in cooking because of its strong flavor, it is the most extensively used of all the mints both medicinally and commercially. It’s known for flavoring toothpaste and chewing gum as well as an extensive amount of cosmetic products.
Peppermint is a natural hybrid of Spearmint (M. spicata) and Water Mint (M. aquatica). In its wild form it is known as Mentha balsamea and can be found growing along streams and waterways in both its native region of the Mediterranean as well as in its naturalized regions, often near where it was once cultivated commercially. This herbaceous perennial grows most often about one to two feet tall but can reach heights of three to four feet and is cold hardy in USDA zones 3 to 8. Its dark green leaves are toothed and pointed, about three inches long and exhibit reddish veins. Its stems are usually red and smooth though some cultivars have green, hairy stems. The leaves emit a strong odor when crushed and leave a cooling sensation in the mouth and throat when consumed. Its prolific pink or purple flowers form on spikes from mid-June to late July.
Like most mints, mice, chipmunks, and squirrels don’t like the smell and growing Peppermint near a home helps to repel these critters. Its oil has a high concentration of natural pesticides, mainly pulegone, which is known to repel some insect pests including mosquitos. Cuttings of Peppermint can be bruised and tossed under brassicas in the garden to repel cabbage moths and as long as they are replaced with fresh cuttings weekly, can lead to a worm-free brassica crop. Since Peppermint oil contains some antiviral and antifungal properties, it is an ideal additive to cleaning products.
Dried leaves of Peppermint were found in Egyptian pyramids dating back to 1000 B.C.E. The first botanical description of Peppermint was made by Linnaeus from plants he had collected in England. He treated it as a new species of Mint but it is now known that it is a naturally occurring hybrid of Spearmint (M. spicata) and Water Mint (M. aquatica). This means Peppermint is a failly new addition to the Mint family. Its first known cultivation was in England. Its medicinal qualities were quickly realized and in 1721 it was admitted into the London Pharmacopoeia.
Peppermint is now the most extensively used of all the volatile oils, both medicinally and commercially. The U.S. is currently the world’s largest producer of Peppermint oil. In 2018, the U.S. produced enough Peppermint oil to fill an Olympic-sized pool – that’s 5.38 million pounds worth! About 90% of the U.S. ‘s cultivation of Peppermint occurs in the Pacific northwest which has the kind of climate the plant loves – moist with cool nights and warm days with more than 14 hours of sunlight during the Winter months. It is also cultivated in Idaho, Indiana, and Wisconsin. Prior to WWII Japanese mint oil (M. arvensis L.) was the leading source of menthol used in American products, such as cough drops, tobacco, fragrances, pharmaceuticals, and candy. After the bombing of Pearl Harbor, menthol was extracted from American-grown Peppermint. It was considered an essential war crop due to its high demand. During WWII Washington state’s acreage devoted to Peppermint cultivation expanded from 1,800 acres in 1941 to 4,200 acres just five years later.
Peppermint is a sterile hybrid and doesn’t produce viable seed. It is propagated instead by stem cuttings, runners, division, and layering.
Peppermint plants should be spaced 18-24” apart.
Peppermint prefers a cool, moist climate with well-draining, loose, organically-rich soil. It will thrive in a partial shade to full sun but its flavor is better when grown in full sun. In full shade, it grows more sprawling, like a groundcover. It’s important to alway keep Peppermint well watered for optimal growth. The plant struggles in dry conditions. In order to get the highest concentration of oil, however, it is good to let the soil dry out a little between waterings when approaching harvest time. If growing Peppermint in a dry or hot environment, adding a layer of organic mulch around plants helps retain moisture and keep the plants thriving.
Peppermint grows quickly and vigorously, first into a small, busy shape before sending out runners that can root along the ground wherever they can touch. Leaves will grow more sparsely on the runners and it’s at this point you’ll want to be diligent about keeping it cut back if you hope to slow its spread. The plant grows so prolifically that some commercial growers plow up their plants in the Fall, chopping the roots and runners and spreading them around, so that in the Spring, new plants pop up everywhere.
To keep Peppermint doing its best, it needs to be “renewed” every 2-3 years. Do this by digging it up, dividing the roots and replanting them. The ideal time to harvest is just as the plants start to bloom. This is when the oil concentration and flavor are at their peak. Mints should be harvested early in the day for the strongest flavor. Peppermint can be used fresh or dried. Drying the leaves causes it to mellow and lose some of its menthol flavor.
Peppermint is a sterile hybrid that does not produce viable seed.
- Pest repellant
Peppermint is not used in cooking as much as Spearmint because of its strong flavor, though it still has many applications in the kitchen. It is often used to flavor sweets, such as chocolate desserts, ice cream or the confection Peppermint bark. It can be chopped fine and mixed into potato salad or coleslaw. It’s a great addition to beverages, both hot and cold. Add it to lemonade, iced tea, or cocktails. Add it to hot chocolate and hot tea. Fresh or dried, it can complement lamb, poultry, or fish dishes. Just be sure to use it in moderation so as to not overwhelm your dishes with its flavor.
Peppermint has a very long history of use and its essential oil constituents of menthol and menthone have been the focus of many research studies. Traditionally, Peppermint has been used for indigestion, flatulence, bloating, nausea (including motion sickness), tension headaches, and as a decongestant. Topically, it is used for balms and ointments for muscle pain, nerve pain, and for relief from itching. Peppermint induces sweating and has been used to bring down fevers. Dried, powdered Peppermint is often added to tooth powders and its antimicrobial properties are said to help with receding gums and gingivitis.
The oil is known to produce a relaxing effect on the digestive system and several studies have shown that enteric-coated Peppermint capsules can help treat the symptoms of Irritable Bowel Syndrome including pain, bloating, gas, and diarrhea. Menthol, its main active ingredient, is found in the leaves and flowering tops. It is the menthol that provides the cool sensation of the herb. The menthol content of the oil varies depending upon the climate and habitat where it is grown. American Peppermint oil contains anywhere from 50-78% menthol. English Peppermint oil contains 60-70% menthol and Japanese Peppermint oil contains 85% menthol.
Because of Peppermint’s relaxing effect on the digestive system, it is not to be used with GERD or hiatal hernia. The amount normally found in food is likely to be safe during pregnancy and it does have a history of being used for pregnancy induced nausea, but not enough is known about the effects of larger supplemental amounts and these larger amounts should be avoided in pregnancy. Peppermint can lower blood sugar and can make gallstones worse so should be avoided in any conditions where this may be an issue. It can interact with certain medications such as cyclosporine, drugs to treat diabetes, medications metabolized by the liver, and antihypertensives. It should not be given to an infant or small child and Peppermint oil should never be used on or near infants as its menthol content can cause life-threatening breathing problems.
Peppermint is believed to have originated in the Mediterranean regions of Europe and the Middle East. It is grown in many regions around the world and can be found growing wild and naturalized, often in regions where it has been grown for oil production. It is considered invasive in Australia, the Galapagos Islands, New Zealand and in the Great Lakes regions of the U.S.