Scarlet bee balms, Monarda didyma, are beautiful clumping, summer blooming perennials with a spreading habit. Easy to grow, most are winter hardy in Zones 3 through 4 and 8 through 9. These native North American members of the mint family produce fragrant, edible flowers and foliage. The brilliant 1½-inch scarlet blooms boast copious amounts of nectar that hummingbirds and bumblebees find irresistible.
Plant scarlet bee balms in full or lightly dappled sun in a well-draining location. Dig the hole so that it's large enough to position the plant without crowding or crushing the roots. Mix about one part peat moss into four parts of backfill soil, and plant the bee balm at the same depth it occupied in its growing container.
Water the plants enough to keep the soil evenly moist, but don't allow them to become wet or saturated. Apply a layer of mulch to help retain necessary soil moisture and help inhibit weed growth. Keep bee balms moist throughout the growing season.
Feed scarlet bee balm plants a single application of fish emulsion each spring. Avoid any further fertilizing. Scarlet bee balms don't like being overfed, but powdery mildew does.
Cut flower heads from the bee balm plants as soon as they fade to extend the summer blooming period, June through August or even a little later. If you want the plants to reseed, leave the final flushes of dead blooms on them.
Treat bee balms for powdery mildew if it occurs on fading foliage during late summer or into the fall, typically when warm days are followed by damp, cool evenings. Spray once weekly with a solution of two tablespoons of baking soda and three tablespoons of horticultural oil dissolved in a gallon of water. Alternately, spray with commercial fungicide, if you must, according to the manufacturer's recommendations.
Cut the infected stems back to ground level. Remove the infested debris immediately and destroy it to eliminate as many fungus spores as possible. If it's early enough in the season, chances are excellent that the plants will quickly sprout another quick round of blooming. Spray the returning foliage weekly with a solution of five parts water and one part milk to discourage future infestations.
Divide and replant scarlet bee balms annually, beginning in their third or fourth spring seasons. The clumps have a tendency to become overly thick. Remove and discard any plants within the clumps that have become unattractive. The remaining plants will quickly repopulate any cleared areas. Most cultivars reseed enthusiastically but don't grow true to parent, so this is also the best way to propagate scarlet bee balms.