Common name for Melissa officinalis, an aromatic, sweet herb of the Mint Family grown in the herb garden for seasoning, and also used in liqueurs and historically, as a medicine. Lemon balm grows to 2 feet tall and has small 2-lipped flowers in late summer, and leaves of a decided lemon odor and flavor.
Of Old-World origin, it is widely naturalized in America. It is easily propagated by division or alternatively, by seeds sown in garden beds or coldframe.
Growing the Herb Lemon Balm
Lemon balm is relatively easy to cultivate outdoors in United States Department of Agriculture Plant Hardiness Zones 4 through 9. In zone 4, it needs winter mulch and a well-drained sandy soil to survive.
In zone 7, it can be harvested at least until the end of November. It is moderately shade-tolerant, much more so than most herbs. In dry climates, it grows best in partial shade.
Lemon balm grows in clumps and spreads vegetatively as well as by seed. In mild temperate zones, the stems of the plant die off at the start of the winter, but shoot up again in spring. It can be easily grown from stem cuttings, or from seeds. Under ideal conditions, it will seed itself prolifically and can become a nuisance in gardens.
Lemon Balm Growing Cultures
Outdoors, in containers, and hydroponics.
Lemon Balm Plant Height
Lemon balm usually grows to a height of 12 to 18 inches (30 -45cm).
Lemon Balm Plant Spacing
Lemon balm plants should be spaced between 12 and 15 inches (30 and 38 cm) apart.
Lemon Balm Preferred pH Range
Lemon balm will grow in a relatively wide pH range between 5.6 (acidic) and 9.0 (strongly alkaline) with a preferred range of 6.0 to 7.5.
Lemon Balm Propagation
From seed. Start seeds indoors six to eight weeks before last frost.
Lemon Balm Seed Germination Period
Lemon balm seeds germinate between 12 and 21 days.
Lemon Balm Number of Seeds per Gram
There are approximately 2,000 Lemon balm seeds per gram.
Lemon Balm Soil Requirements
Lemon balm prefers a fertile, well-drained clay or sandy loam.
Lemon Balm Alternative Growing Media
Soilless potting mixes (Pro-Mix, Sunshine Mix, etc.), perlite, vermiculite, rockwool, coco peat, Oasis Rootcubes.
Lemon Balm Time From Seed to Saleable Plant
Seeds to finished plugs, 6 weeks; plugs to saleable plants, 5 weeks.
Lemon Balm Sun & Lighting Requirements
Lemon balm grown outdoors prefers full sun, but is mildly shade-tolerant. In dry climates, it grows best in partial shade.
Lemon balm will grow indoors satisfactorily under standard fluorescent lamps, and exceptionally well under high output fluorescent, compact fluorescent, or high intensity discharge (metal halide or high pressure sodium) plant growing lights. Keep standard fluorescent lamps between 2 and 4 inches from the tops of the plants, high output and compact fluorescents approximately one foot above the plants, and HID lights between 2 and 4 feet above the plants, depending on wattage.
Have an oscillating fan gently stir seedlings for at least 2 hours per day to stimulate shorter, sturdier, and more natural plant habit.
Lemon Balm USDA Hardiness
Perennial. Zones 4a to 9b.
Lemon Balm Water Requirements
Requires consistently moist soil, do not let soil dry out in between waterings. Water on a regular schedule, taking care to not overwater.
Lemon Balm Potential Plant Pests and Diseases
Lemon balm can be susceptible to whitefly, spider mites, thrips and powdery mildew.
Lemon Balm Special Notes
Lemon balm may be considered a noxious weed or invasive plant in some areas. Lemon balm is drought tolerant and is useful in xeriscaping. Lemon balm is known to attract bees, butterflies and birds and has fragrant blossoms.
Lemon balm self-sows freely; remove flowers (deadhead) if you do not want volunteer seedlings the following season.