These members of the mint family form bushy, leafy clumps that grow 1-1/2- to 4-feet tall. The oval, dark green leaves have toothed edges, and have a strong scent of mint with overtones of other herbs, some rose-flavored, some lemony. Like all mints, stems are distinctly four-sided. In summer and fall, tight clusters of long, tubular, and nectar-rich flowers appear atop stems. Depending upon the variety, flowers are pink, white, blue, violet, purple, or scarlet.
Perennial clumps spread by underground rhizomes. They're not as invasive as mints, but can overwhelm a nearby lavender, for instance. Annual bee balms do not spread by rhizomes.
Bee balms are native to North America, from Vermont to Florida, and from Texas to British Columbia. Few plants make so little demand on the gardener. Annual bee balms do seem to prefer sandy, acidic soils and full sun, but perennial kinds thrive in a range of soils. Most grow best given full sun or partial shade, reasonably fertile and moist soil, and a compost mulch.
Propagate annuals from seed sown in place in late spring. Increase perennials either from seed sown in a cold frame in early spring, or (better) from division in fall or spring of established clusters. Set transplants about 10 inches apart. Plants tend to thin or die in the center as they grow outward, a habit that makes division necessary every three to four years.
Bee balms are not long-lived where winters are mild, or where summers are long and hot. Most kinds grow best in USDA Hardiness Zones 4 through 8. The one serious pest of Monarda didyma, mildew, is exacerbated wherever summers are hot and dry. The best bet is to plant mildew-resistant varieties (see following section), or any of the other species that are not susceptible.
Combine bee balms with other herbs, vegetables, and roses in borders, cutting gardens, containers, and naturalistic settings. They are handsome summer- and fall-bloomers, and clumps look good near water. Their flowers are long-lasting and striking in arrangements. Both leaves and flowers are used in potpourris and tussie-mussies (a bouquet of herbs).
Of the dozen or so identified bee balm species, the following five and their varieties are the most useful for gardeners.
Lemon bee balm (M. citriodora). Annual, all zones; can be grown as a short-lived perennial in mild-winter regions (zones 8 to 11). As its name implies, this one (native to the southern and southwestern United States) is noted for its citrus scent. It is one of the shorter types (2 1/2 to 3 feet tall), which makes it perfect for borders. Bloom season is long, hummingbirds love the pale lavender flowers, and blooms make excellent arrangements.
Generally the varieties with red flowers prefer more shade and moisture, while those with lavender or white flowers do best in sunnier, drier conditions. (Many of these named varieties of M. didyma are hybrids of M. clinopodia, M. didyma, and M. fistulosa. Some botanists refer to the entire group as M. media.)
Wild bergamot (M. fistulosa). Perennial; zones 3 through 9. Wild bergamot (no relation to true bergamot, a citrus) grows in dry, open woodlands and wood margins, primarily in eastern North America. It thrives in places that have cool summers, conditions typical in the heart of its native range from New England to Georgia. Compared with other bee balms, wild bergamot is less showy, stems are more noticeably four-sided, and leaves are a little hairier, more sweetly fragrant, and less toothed than those of M. didyma. Lavender-pink flowers come in late summer, the newest flower developing above the older ones. Height is 3 to 4 feet.
'Rose;', a new variety, is notable for smelling and tasting in all its parts like an old-fashioned rose. It's an ideal fragrance and flavor substitute for rose geranium where that plant isn't hardy.
The closely related M. f. menthifolia grows in western North America. When dried, it substitutes well for oregano.
M. pringlei. Annual or short-lived perennial; all zones. Though this stunning bee balm reaches only 18 inches tall, bees, butterflies, and hummingbirds cover it throughout its long blooming season that begins in late spring or early summer and continues until frost. Its glossy, dark green mounds of foliage remain green during the winter in zones 7 to 11. This species does not get powdery mildew.
Spotted horsemint (M. punctata). Annual or short-lived perennial; all zones. This 2-foot plant is extraordinary in bloom, producing tiers of showy pink bracts, and dense whorls of purple-spotted yellow flowers. Bloom starts in early summer and lasts until frost. Start plants from seed sown in place in early spring. Plants tolerate dry soil (even prefer sandy soil), and rarely suffer from powdery mildew. Spotted horsemint contains the greatest concentration of thymol.
Holly Shimizu is the director of the U.S. National Arboretum and an herb specialist.
Photography by Suzanne DeJohn/National Gardening Association