Bee balm (Monarda didyma) sends up dense clusters of scarlet flowers in midsummer, and it often remains in bloom for a month or longer. The flowers attract butterflies, bees and hummingbirds to your flower bed, making it a suitable choice for a low-growing shrub or an anchor plant in the garden. Bee balms are hardy in U.S. Department of Agriculture plant hardiness zones 4 through 9, where they require little maintenance to thrive. Removing the old flowers, a process called deadheading, and pruning correctly improves both the appearance and health of the bee balm.
Bee balm flowers don't retain any ornamental qualities after they fade. The formation of seeds can cause the quick decline of the foliage so the whole plant begins to die back before the end of the growing season. Removing the spent flowers prevents foliage loss and may encourage a second weaker flush of flowers, extending both the growing and the flowering season of the small shrub. Deadheading and pruning also increases air circulation, which can help prevent powdery mildew and fungus problems.
Handheld pruning shears can handle the summer pruning needs of bee balm. Bypass shears work better than single-blad varieties because they make a clean cut without crushing the stem. Clean and disinfect the shears thoroughly before you begin deadheading and again after each plant to minimize the spread of diseases, pests or fungal spores. Wiping the shears with a cloth soaked in isopropyl alcohol allows for quick disinfection as you prune. Washing your hands before pruning and wearing gloves also helps prevent the spread of disease.
Begin deadheading as soon as the first flower clusters begin to wilt and die. Cut back the flowering stems to within 1/4-inch of a leaf or leaf bud near the top of the stem. After deadheading, rake up and dispose of or compost the removed flowers. Bee balm begins flowering in midsummer and each flower cluster can persist for several weeks. Checking the plants weekly for wilting clusters allows for prompt removal of the older flowers so their seed production doesn't weaken the plant.
Cutting back the entire bee balm after the first major flowering flush is over removes any remaining flower clusters and rejuvenates the foliage for the remainder of the growing season. Remove up to one-third of the plant from the top, trimming off both the old flowers and foliage. The bee balm usually responds with a flush of new growth and flower bud production, although this second flowering is not as lush as the first. You can also cut back the bee balm by half its height in mid-spring before it begins to flower to encourage fuller foliage and more flower buds, but this treatment may delay flowering by a few weeks.