Bee Balm (Monarda spp.) offers stunning flowers in shades of red, purple, or pink. Hardy in Zones 4 – 9, it is very popular among hummingbirds and pollinators.The best time to prune these perennials is in the fall. However, because Bee Balm is susceptible to powdery mildew, you’ll want to cut back the leaves and stems, then dispose of the cuttings in the trash — not in your compost bin!