Lemon Balm (Melissa officinalis L.)

Lemon balm (Melissa officinalis L.) is a lemon scented member of the mint family. A native to southern Europe, it is a perennial which will over-winter in hardiness zones 4 to 5.

Its foliage has a distinctive lemony fragrance when bruised. The leaves are light green, crinkled, slightly hairy, and strongly toothed on the margins, more or less egg shaped, and about 1-3 in (2.5-7.6 cm) in length. As is typical of herbaceous mints, lemon balm leaves are arranged in opposing pairs on square stems. The little flowers are 0.5 in (1.3 cm) in diameter are produced all summer long. They are pale yellow maturing to pale lilac and arranged in irregular whorls at leaf nodes on upright stems. The flowers are not at all showy and the plant is generally grown for its lemon scented leaves. A mature lemon balm plant can stand 2-3 ft 0.6-0.9 m) tall and spread and sprawl 2-3 ft (0.6-0.9 m) across. ‘All Gold’ is a selection with yellow leaves, and ‘Variegata’ (a.k.a. ‘Aurea’, has dark green leaves with golden yellow markings along the margins.

Culture
Grow lemon balm in any well-drained soil; it tolerates poor, sandy soils and full sun.
Light: Lemon balm tolerates full sun or partial shade, and the yellow leaved cultivars produce the best color in light shade. In hot climates, lemon balm likes partial shade at midday, and seems to thrive in the understory of larger, leggy mints like members of the genus Salvia and Monarda.
Moisture: Lemon balm is tolerant of droughts and should be kept dry in winter.
Hardiness: USDA Zones 3 – 9.
Lemon balm is easy to grow from seed sown in the spring or early fall. The seed is very small and should be covered with only a fine layer of soil. Cuttings and root divisions, however, are faster and easier ways to establish lemon balm. Stem cuttings can be made from the vigorous summer growth or the roots can be divided in the spring or fall. Root cuttings should contain three to four buds each. In the fall, plant root cuttings early enough for the plants to become established before the first frost and mulch for the winter. Suggested spacing is 12 to 24 inches apart in the row and 24 inches, or whatever distance is practical for cultivation, between the rows. Close spacing of rows and individual plants will result in the highest yields. When choosing a site, keep in mind that lemon balm self-sows freely, spreads rapidly and can quickly become a weed.

Fertilization – Although specific recommendations are not available for fertilization of lemon balm, for mint production 80 to 100 pounds of nitrogen, 100 pounds of phosphorus and 400 pounds of potash per acre are often recommended. Yield and oil content may be increased by side dressing with nitrogen several times during the growing season.

Irrigation – Provide a regular supply of water through drip or overhead irrigation.

Weed Control – Currently, there are no herbicides cleared for use on lemon balm in North Carolina. Weed control is important, however, because the presence of weeds in the dried product will reduce quality and, consequently, price. Shallow cultivation and the use of plastic or organic mulches are recommended.

Disease and Insect Control – There are no pesticides registered for lemon balm. Prevention of disease through good cultural practices is the most effective means for healthy crop production. To reduce the incidence of soil borne diseases, rotate plantings of lemon balm to soils that have not been used for cultivation of another member of the mint family for several years. To prevent foliar diseases, keep foliage as dry as possible by watering early in the day or by using drip irrigation. Insects are not usually a problem on lemon balm. If populations become unacceptably high, however, various organic controls such as beneficial insects, traps, mild soap solutions and hand-picking, can be tried. Before spraying any homemade insecticide solution on a crop, test for adverse effects to the foliage by spraying a small area first and observing for a day or two.

Harvest and Handling – Lemon balm can be harvested for fresh sales once or twice a week. Frequent trimming encourages branching and will result in a bushy, compact plant. For a dried product, harvest at least twice a season just as the plant comes into bloom. For large scale operations, foliage can be cut with a side-bar cutter. An acre may produce 1000 pounds or more of dried herb. Be careful not to bruise the leaves during the harvest and drying operations as quality will be reduced. Although lemon balm dries quickly and easily it will not be as fragrant dried as fresh. It can be dried outside in partial shade but will brown quickly if there is any night moisture. Plants may also be hung in bunches and air dried in a shed or barn or oven dried on screens. When dry, store in tightly closed containers. If hung to dry in bunches, lemon balm can be rapidly processed by rubbing each bundle across a half-inch mesh screen to crumble the leaves.

Uses – Lemon balm, with its delicate lemon scent and flavor, is valued as a culinary, cosmetic and medicinal herb. Fresh sprigs are used to top drinks and as garnishes on salads and main dishes. Fresh or dried leaves make a refreshing tea, either iced or hot. Dried leaves are used as an ingredient in many potpourris and the oil is used in perfume. Used throughout history as a medicinal herb, lemon balm has mild sedative properties and has been used to relieve gas, reduce fever, and increase perspiration. The volatile oil contains citral, citronellal, eugenol acetate and geraniol. Both oil and hot water extracts of the leaves have been shown to possess strong antibacterial and antiviral qualities.

Features
There are only three species in the genus Melissa, which is from the Greek word for bee, referring to the strong attraction the plant holds for honeybees. “Balm” is short for balsam, a term used for many fragrant plants. Lemon balm has a long history of use in Europe where it has been esteemed for curing all sorts of ills and wounds, both psychological and physical. According to A Modern Herbal, the London Dispensary, published in 1696, says: “An essence of balm, given in canary wine, every morning will renew youth, strengthen the brain, relieve languishing nature and prevent baldness.” What more could you want? Actually, modern research has shown that some of the volatile oils in lemon balm, namely citral and citronellal, have a calming effect on the central nervous system and are antispasmodic. Also, some of the polyphenols in lemon balm are anti-viral in activity and have been shown to reduce the duration of cold sores and to increase the time between cold sore outbreaks.

References

• Foster, S. 1984. Herbal Bounty! The Gentle Art of Herb Culture. Peregrine Smith Books, Salt Lake City.
• Foster, S. 1993. Herbal Renaissance. Peregrine Smith Books, Layton, Utah.
• Green, R.J. 1985. Peppermint and spearmint production in the Midwest. The Herb, Spice and Medicinal Plant Digest 3(1):1-5.
• Miller, R.A. 1985. The Potential of Herbs as a Cash Crop. Acres U.S.A., Kansas City, Missouri.