In July and August, the attractive flowers of bee balm (Monarda) are a common sight in gardens, along roadsides, and in prairies. Bee balm attracts bees, butterflies, and hummingbirds. The common name of bee balm is in reference to its former use to treat bee stings. Other common names include bergamot, horsemint, and Oswego tea. When sited properly and given good care, bee balm is a wonderful, easy-to-grow perennial for the home landscape.
Three species of Monarda (Monarda didyma, Monarda fistulosa, and Monarda punctata) are native to Iowa. Numerous cultivated varieties are available at garden centers.
Bee balm flowers are borne atop the plants. The slender, tubular flowers are produced in 2- to 3-inch-wide flower heads in June and July. Flower colors include white, pink, red, lavender, and purple.
Bee balms perform best in moist, well-drained soils in full sun. The planting site should receive at least 6 hours of direct sun each day. Plants won't flower as heavily and are more susceptible to powdery mildew when grown in partial shade.
Bee balms like an even supply of moisture during the growing season. For best performance, water plants every 7 to 10 days during dry periods. When watering, soak the soil to a depth of 6 to 8 inches. Apply a mulch around plants to conserve soil moisture and reduce the frequency of watering.
Bee balms don't require frequent or heavy fertilizer applications. Sprinkling a small amount of all-purpose garden fertilizer, such as 10-10-10, around each plant in early spring is usually sufficient. Avoid over-fertilization. Frequent or heavy applications of fertilizer encourage rampant, succulent growth and may increase the severity of powdery mildew, a common disease on bee balm.
Promptly remove spent flower heads to prolong the bloom period of plants and improve the plant's appearance.
Bee balms spread rapidly via underground stems or rhizomes. In addition, the centers of the clumps often die out within a few years. To control their spread and rejuvenate plants, it's advisable to dig and divide bee balms every 2 to 3 years. Early spring is the best time to dig and divide bee balms. Dig up plants as soon as they emerge from the ground. Divide the clump into sections with a sharp knife. Each section should have at least 2 or 3 shoots and a good root system. Replant immediately.
Insect and Disease Problems
Bee balms may occasionally suffer some minor insect damage. However, the fungal disease powdery mildew is the most common problem. It appears as a grayish white ‟powder" on the upper leaf surfaces. Severely infected leaves drop prematurely. Disease symptoms are most severe on overcrowded plants, those growing in partial to heavy shade, and drought-stressed plants.
Cultural practices can reduce the severity of powdery mildew. When planting bee balms, select a site in full sun and space plants 2 feet apart. Divide plants every 2 to 3 years and water during dry periods. Remove and destroy disease-infested plant debris in fall. The fungal spores of powdery mildew survive the winter on disease-infested plant debris. The removal and destruction of this material removes the source of next year's infection.
The best way for home gardeners to avoid the annoying problem of powdery mildew is to select mildew-resistant cultivars. Cultivars that possess good mildew resistance include:
- 'Marshall's Delight' (bright pink flowers)
- 'Gardenview Scarlet' (scarlet-red flowers)
- 'Violet Queen' (violet-blue flowers)
- 'Raspberry Wine' (wine-red flowers)
- 'Colrain Red' (purplish red flowers)
The native species and most older bee balm cultivars grow 2 to 4 feet tall. However, a number of dwarf cultivars have been introduced in recent years. These plants are great additions to the garden, possess good resistance to powdery mildew, and are less likely to grow lanky or floppy.
Dwarf cultivars to consider for Iowa include:
- 'Petite Wonder' (pink flowers; 10 and 15 inches tall)
- 'Petite Delight' (rose pink flowers; 10 and 15 inches tall)
- 'Pardon My Pink' (pink flowers; 10 to 12 inches tall)
- 'Pardon My Lavender' (pinkish purple flowers; 10 to 12 inches tall)
- 'Pardon My Purple' (fuchsia-purple flowers; 10 to 12 inches tall)
- 'Pardon My Cerise (pinkish red flowers; 10 to 12 inches tall)
Intermediate-sized cultivars for Iowa include:
- 'Grand Parade' (lavender purple flowers; 13 to 16 inches tall)
- 'Grand Mum' (mauve pink flowers; 15 to 18 inches tall)
- 'Grand Marshall' (fuchsia-purple flowers; 14 to 20 inches tall)
Updated from an article that originally appeared in the July 14, 2017 issue of Horticulture and Home Pest News.