While lemon balm (Melissa officinalis_) and lemon mint (_Monarda citriodora) are both members of the extensive mint family (Lamiaceae_), they are not closely related. Lemon mint is one of the many species in the bee balm genus (_Monarda spp.) and lemon balm and its cultivars form their own genus (Melissa spp_.)._ Additionally, they grow in different areas of the country. In the United States, lemon balm, a perennial, is found in zones three through seven, while lemon mint, an annual or tender perennial, grows in zones five through nine.
Lemon balm is a lemon-scented, sprawling herb that forms a clump up to two feet high and three feet wide, although is often clipped to a more compact form. Beginning early in the summer, its crinkly, ovate foliage emerges first, followed by spiky, pale-yellow flowers that last late into the summer. Cultivars of common lemon balm include golden-leaved, variegated and lime-scented types.
Gardeners often choose to plant this herb as it's well-known as a bee attractant and adds a pleasant fragrance to the garden. In the kitchen, home cooks use lemon balm in herbal teas, as a garnish for fruit salads or to add citrus flavor notes to seafood, poultry, cheesecake and other dishes that normally pair well with lemon.
One of the more compact of the bee balm group, lemon mint seldom grows taller than 30 inches or broader than 24 inches. Its shaggy-headed, pastel purple or pink flowers appear from early to late summer.
Like lemon balm, lemon mint's narrow leaves produce the plant's distinctive citrus scent, which is most noticeable when you brush against the plant or crush its leaves. Gardeners often plant lemon mint in the sandier or rockier sections of a fragrance garden and in bee and butterfly gardens. Lemon mint is also ideal to use in herbal teas, salads and potpourri blends.
Similarities and Differences
Like a botanical Venn diagram, lemon mint and lemon balm can flourish in some of the same conditions. Both herbs grow best in either full sun or partial shade, and both can take a bit of neglect. Both lemon balm and lemon mint have the potential to become invasive. Lemon balm spreads by underground runners. Dig up the plant every few years and divide its roots, and keep its above-ground portions clipped back. Keep lemon mint or lemon balm in a container if spreading runners are a concern. Because lemon mint sometimes self-seeds, be vigilant about pulling up its seedlings adjacent to your lemon mint patch or container.
Although lemon balm and lemon mint thrive in moderate climates, their full ranges of tolerance to both weather and soil differ. Lemon balm can withstand cold winters yet wilts in hot climates. In contrast, lemon mint typically dies in winter regions where it grows as an annual, yet sometimes returns through self-seeding or by underground runners, especially in mild climates. Although both herbs will thrive in a range of soils, lemon balm prefers a neutral pH level of about 7.0 while lemon mint does best in chalky, lower-pH soil.