Guidance for Gardeners: trimming perennial stems
Gardening practices are an important aspect of a successful pollinator garden, including winter clean-up. Applied Ecology Associate Professor Elsa Youngsteadt with colleagues from Entomology & Plant Pathology, NC State Extension and Extension Master Gardener℠ have published an Extension article on how to tidy up your garden based on an NC State Extension research project.
Extension agents and Extension Master Gardener℠ volunteers sampled stems from 20 gardens in 10 counties across North Carolina. They sent nearly 3,000 stems to the lab, collected during all four seasons (winter, spring, summer, and fall). These stems were then examined to determine if they were occupied with nesting bees.
The results of this study showed that stems are not occupied in their first winter, and this is a good time to trim them. However, if stems were trimmed or damaged during the growing season, bees could potentially be occupying those stems and should not be trimmed again. Once a stem is trimmed, there is a chance that it is being used by a bee for a nest and should not be disturbed.
11 species of bees and solitary wasps were found nesting inside study stems. Most nests belonged to small carpenter bees in the genus Ceratina. Other bees found nesting in stems included small mason bees (Hoplitis), leafcutting bees (Megachile), and yellow-faced bees (Hylaeus), as well as solitary wasps, including grass-carrying wasps (Isodontia) and mason wasps (Euodynerus and Leptochilus).
