How to Prune Bee Balm

Grown for their aromatic foliage and showy blooms that attract butterflies and hummingbirds, bee balm plants (Monarda spp.) make an easy-care addition to the garden. Pruning and trimming bee balm helps keeps the plants bushy, encourages more flowers and reduces disease.

Hardiness varies by species, and the genus Monarda includes more than a dozen types of annual and perennial bee balms. Common bee balm (Monarda didyma) is hardy in U.S. Department of Agriculture plant hardiness zones 4 though 10. Other plants often called "bee balm" include wild bergamot (Monarda fistulosa), hardy in USDA zones 4 through 8, and horse mint (Monarda punctata), hardy in USDA zones 4 through 9.

Bypass pruners

Hedge shears

Household bleach

Fan rake

Trimming bee balm in the spring delays flowering for a few weeks, but it is well worth the wait to get plants with a bushier, more compact shape. Timing varies by species, and you can skip some pruning tasks if you're growing annual bee balm.

For established clumps of perennial bee balm that are starting to get crowded, thin plants in the spring once the plants have grown at least a couple inches tall. This improves air circulation and reduces problems with mildew. Use bypass pruners to remove one-third of all the bee balm stems by cutting them off at ground level. Trim evenly throughout the clump.

Whether growing annual or perennial bee balm, removing the growing tips encourages branching growth. You can do this one of two ways: pinching or shearing. To pinch plants, use your fingernails to remove the top few leaves on each growing stem. Pinch plants just above a leaf node, the place where leaves attach to the stem.

If you have a large clump of bee balm and want to work faster, you can use hedge shears to cut bee balm back by one-half instead of pinching. Try to cut above the leaf nodes as much as possible, and use a smooth cutting motion to avoid ragged edges or tears.

Both shearing and pinching should be done in the late spring, before plants reach a third of their mature height. For common bee balm, which grows up to 3 feet tall, this means shearing plants down to 6 inches when they reach 12 inches tall.

Always disinfect your pruning tools before use, and in between cutting different plants. This prevents the spread of disease. To sterilize cutting tools, soak them in a solution of 1 part household bleach and 3 parts water, then rinse tools with clean water.

Trimming annual and perennial bee balms in the late summer or fall is optional, but can encourage repeat blooming and result in healthier plants. You could also leave your bee balm alone and let it go to seed, since the seed will attract wildlife and birds.

If you want your annual or perennial bee balm to flower more than once in a growing season, remove the spent blooms as they appear so the plants don't put their energy into producing seeds. Use disinfected bypass pruners for this task, or pinch the flower heads off with your fingernails. Always cut or pinch above a leaf node.

Bee balm is prone to mildew, especially if the plants are crowded. This is rarely life-threatening for the plant, but gives the leaves an unattractive powdery-gray look. After flowering, the plants should have new growth at the base that is mildew-free. If your plants have mildew or your choose to remove the top growth after flowering, use hedge shears to cut the plants back to the new growth. Use a fan rake or your hands to clean up and remove the mildewed stems and foliage. This type of pruning is most important for perennial plants.