Brown coneflower stalks and dried bee balm may look like garden debris once fall arrives, but to some insects, those hollow stems look more like real estate. Native solitary bees, beneficial wasps, moths, spiders, and other small creatures can use dead plant material for nesting or shelter, which means an aggressive fall cleanup can remove habitat along with the mess. Researchers at NC State examined nearly 3,000 perennial stems from 20 gardens in 10 North Carolina counties to learn exactly when stem-nesting bees move in. Their findings offer a more useful approach to cutting back perennials for pollinators than simply telling gardeners to leave everything untouched indefinitely. The trick is knowing the difference between this year’s newly dead stems and older stems that may already have residents inside.
