Lemon balm, also known as lemon mint, is a low maintenance perennial herb of the mint family. It can grow to a height of around 2 feet, and produces ovular to heart-shaped leaves about 2 to 3 inches in diameter. In late spring to summer, the lemon balm plant produces small, light blue flowers. However, it is most often grown for its lemon scented and flavoured leaves, rather than for its appearance, which has been described as "weedy."
Soil Requirements and Planting
Lemon balm plants will thrive in average moist soil with a pH of between 5.0 and 7.5. They are the plants of choice for many gardeners with problem soil or soil prone to erosion. Cool areas of partial shade are ideal, but the plants will also tolerate full sun or full shade, making them very easy to grow in most locations.
Lemon balm can be grown from seed in the early fall or spring. Seeds may be started indoors or sowed directly into the garden. Cover seeds with a very fine layer of soil, and do not allow them to dry out. Cuttings may also be used, and will result in a more quickly established plant. Plant the cuttings or seedlings 12 to 24 inches apart at a depth of approximately ¼-inch. The plants will self-sow and spread rapidly.
Water and Fertilization Requirements
A regular supply of water is necessary for lemon balm plants. They do very well in damp, moist locations, but the soil should not become overly wet or root rot may occur. A drip irrigation system or soaker hose may be required to provide adequate water if the soil is prone to drying out during the summer months. A sprinkler system will also work, as long as the plants are watered daily during the growing season.
All-purpose fertiliser is best used on lemon balm. It should be applied once during the spring and once again in the fall to promote new foliage growth. Be careful not to over fertilise. While this can cause rapid growth, it will also produce leaves lacking in flavour.
Pests and Diseases
Lemon balm has such a high concentration of natural oils in its leaves, that it is not often bothered by typical plant pests and diseases. However, root rot and powdery mildew have been known to affect plants that are over-watered. Weeds may also become problematic near lemon balm plants, and should be eradicated as quickly as possible. Remove any weeds by hand or use an approved herbicide, according to the manufacturer's instructions.
Harvesting and Use
Frequent harvesting of the leaves will result in a more compact lemon balm plant. It will also increase the yield of fragrant leaves. Harvest about one-third of the leaves prior to blooming at least twice per growing season for best results. Tie stems together, and hang harvested leaves in a cool, shady place to dry. Store the dried leaves in a cool, dry place in an airtight container and use as necessary.
Lemon balm leaves may be used fresh or dried in teas, and will add a lemony flavour to any beverage. Used fresh, they lend their flavour well to marinades for chicken and fish, and can also be used as a garnish. Dried leaves experience rapid flavour loss, but may be used in homemade cosmetics, potpourris and soaps.