Perennial bee balm (Monarda didyma) brings a splash of color and texture and attracts bees and butterflies to your summer garden. In full sun to partial shade, healthy bee balm stands 2 to 4 feet tall with flowers that are pink, violet or red. This plant thrives in U.S. Department of Agriculture plant hardiness zones 4 through 9 and is usually easy to care for, but drooping flowers and foliage are a sign of poor health.
Bee balm requires moist, well-draining soil. Consistent moisture is especially important during the summer months when bee balm is actively growing. Dry soil and drought cause bee balm flowers and leaves to appear lifeless and droopy. In a severe drought, bee balm may die. Provide supplemental water to bee balm once a week when rainfall is less than 1 inch. Soak the soil thoroughly so the root system gets a healthy drink. A layer of mulch 4 to 6 inches deep around the plants keeps bee balm cool and conserves moisture.
When a plant receives too much water, the symptoms mirror some of the same signs experienced due to lack of water. With bee balm, overwatering causes drooping, wilting or lifeless flowers and foliage. This is because too much water prevents the root system from taking in enough oxygen. Bee balm is especially sensitive to too much moisture in the winter months, which leads to problems in the following season’s growth and health. For this reason, plant bee balm in well-draining soils, such as a sand or loam mixture, rather than dense clay soils, which lack good drainage. Some bee balm varieties are bred to be resistant to wet soils, but in other varieties, too much moisture leads to problems with fungal pathogens.
One of the most common diseases to affect bee balm is powdery mildew. Bee balm is particularly susceptible to this fungus. While there are some resistant cultivars, such as “Raspberry Wine,” “Marshall’s Delight” and “Violet Queen,” powdery mildew harms the typical plant's overall health. Symptoms include drooping foliage, wilting and leaves that eventually turn brown, shrivel up, fall off and die. A whitish-gray powderlike substance appears on the tops of infected plant leaves. To protect bee balm plants from powdery mildew infection, provide plenty of breathing room and air circulation. This includes spacing the plants 1 1/2 to 2 feet apart and trimming stems and foliage to allow the movement of air and sunlight. While bee balm tolerates partial shade, full sun reduces the development of powdery mildew. Remove any infected foliage and cut the stems down to the base of the plant. Remove heavily infected plants. Always wear gloves when pruning or handling infected plant material.
The stalk borer is one of the few insects that harms bee balm. Unfortunately, stalk borers are not easily controlled. While wearing gloves, remove and destroy infected plants to prevent further infestation. This 1 1/2-inch-long larva is gray to brown in color and bores its way into the stalks of the bee balm plants. The results include lack of vigor, drooping, wilting and eventually the death of the plant.