How Your Perennial Garden Can Shelter Bees

Pollinator garden enthusiasts, did you know that your perennial plants can support bees long after the flowers have faded?

Stems of the same flowers that produce nectar and pollen for bees can provide shelter later on. In fact, more than 100 species of bees in North Carolina like to nest in hollow stems, twigs or wood, where they spend the winter or raise their young. These solitary native bees aren’t aggressive, and they won’t harm plants.

To find out the best ways to shelter bees in perennial stems, NC State University researchers Elsa Youngsteadt and Hannah Levenson analyzed samples from 20 gardens in 10 counties in North Carolina over two years. Extension agents and Extension Master Gardener℠ volunteers sent in stems to Youngsteadt, an Extension leader and entomologist with the Department of Applied Ecology, and Levenson, a bee expert in the Department of Entomology and Plant Pathology.

What Youngsteadt and Levenson found led them to rethink the recommended timeline for tidying up perennial gardens in North Carolina. To avoid disturbing bees inside the stems, they say it’s best to trim perennials in winter instead of spring. 

Here’s a summary of what Youngsteadt and Levenson recommend for newly planted perennials: 

• As flowers die, leave them on perennial plants through fall so that birds and other animals can harvest the seeds. 
• In early winter, trim the stems of your perennials to a height of 1 to 2 feet. That will create hollow stems that bees can move into starting in January and February of the following year. 
• Leave the hollow stems on your perennials until they fall down on their own. That way you won’t disturb nesting bees.

For details and photos, consult their new Extension factsheet, “Garden Cleanup for Pollinators: Trim Perennial Stems in Their First Winter”

This post was originally published in College of Agriculture and Life Sciences News.