Common Bee Balm Problems and How to Fix Them

Bee balm, or Monarda, is a favorite in many gardens for its vibrant flowers that attract pollinators. While a resilient perennial, it can present challenges that leave gardeners searching for answers. Understanding the common issues that affect bee balm is the first step toward ensuring it remains a healthy part of your landscape.

Common Bee Balm Diseases

The most widespread issue affecting bee balm is powdery mildew, a fungal disease appearing as a white or gray dusty coating on leaves and stems. This fungus thrives in high humidity combined with poor air circulation. While it rarely kills the plant, it can weaken it, reduce flowering, and make it unsightly.

For management, prune and discard the most affected leaves to improve airflow and slow the spread. Simple homemade solutions can be effective, such as a spray of one part milk to nine parts water, or one tablespoon of baking soda with a half teaspoon of liquid soap in a gallon of water. For persistent infections, commercial fungicides are available. If the plant is covered late in the season, cut the stems to the ground and dispose of the foliage.

Bee balm can also suffer from other fungal issues like leaf spot or rust. Leaf spot presents as dark lesions on the foliage, while rust appears as reddish-brown pustules on the undersides of leaves. The same practices that deter powdery mildew are effective against these diseases. Good air circulation and watering at the base of the plant to keep foliage dry are important preventative measures.

Pest Infestations

Several insect pests can trouble bee balm, though they are less of a problem than fungal diseases. Aphids and spider mites are the most common. Aphids are tiny, pear-shaped insects that cluster on new growth, while spider mites are harder to see but create fine webbing on the plant. Both pests feed on plant sap, which can cause leaves to yellow and distort.

A strong spray of water from a hose can dislodge these pests. For more persistent problems, insecticidal soap or neem oil can be applied. Avoid broad-spectrum pesticides to protect the pollinators drawn to bee balm’s flowers. These treatments should be applied thoroughly, covering all leaf surfaces, especially the undersides.

A more damaging pest is the stalk borer, the larva of a moth that tunnels into the plant’s stems, causing the stalk to wilt and die. A sign of a stalk borer is a small entry hole near the base of the wilting stem. Since the pest is inside the stem, surface sprays are ineffective. Prune the infested stalk to the ground to remove the larva and prevent it from moving.

Growth and Flowering Issues

Sometimes bee balm’s problems are related to its growing conditions. A common issue is the development of weak, “leggy” stems that cause the plant to flop over. This is often a result of too much shade or overly rich soil with excess nitrogen fertilizer. These conditions encourage rapid, weak foliage growth instead of strong stems.

To correct this, plant your bee balm in a location that receives at least six hours of direct sunlight daily. Avoid high-nitrogen fertilizers; a layer of compost in the spring is usually sufficient. The “Chelsea Chop,” which involves cutting the plant back by one-third in late spring, can encourage a sturdier, more compact growth habit.

Insufficient flowering is another frequent complaint, and the primary cause is a lack of sunlight. Bee balm needs plenty of direct sun to produce its blooms. If your plant is in a shady spot, it will produce lush foliage but few flowers. Another factor that can reduce blooming is overcrowding, as the plant can become too dense to flower well.

Preventing Future Problems

The most effective strategy for dealing with bee balm problems is prevention. For powdery mildew, selecting a mildew-resistant cultivar from the start is the best defense. Modern hybrids like ‘Marshall’s Delight’ or ‘Jacob Cline’ have been bred for improved disease resistance.

Regular division is important for maintaining a healthy bee balm patch. Every two to three years in the early spring, dig up the entire clump and divide it into smaller sections, discarding the old, woody center. Replanting these divisions provides them with more space and renewed vigor. This practice prevents the overcrowding that can lead to poor flowering and disease.