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Garden Talk

Dried flower stalks of native wildflowers in the Piedmont Prairie

Overwintering for Native Wildlife

By Katherine Hale

Marketing & Communications Assistant

The Piedmont Prairie in the Blomquist Garden of Native Plants contains a diverse assemblage of grasses and wildflowers, most of which die back to the roots with the first hard frost. These dried stems and seed heads remain in place all winter long instead of being immediately cut back, often to the surprise of visitors who expect every dead plant to be immediately removed from the garden. But there are many practical reasons for this decision, beyond the naturalistic aesthetics.

The impulse to organize and tidy a garden over the winter is a natural one, but it’s not so helpful to the animals that call it home. Small mammals, birds, reptiles and amphibians need shelter to protect them from predators, and those that eat fruit, nuts or seeds would lose an important food source. By waiting until spring for the annual cleanup and cutting back, gardeners can help support the surrounding wildlife and become an important refugium, however small, in an era of increasing habitat loss. And because the plants themselves are either dead or dormant during the winter, it makes no difference to them whether they are cut back in late fall after the frost or in the spring.

Leaving the landscape undisturbed until spring is especially important for native insects, whose life cycles often include an overwintering stage, whether as eggs, pupa, or adults in diapause (analogous to hibernation in mammals). This is especially true for bumblebees. Solitary queen bees overwinter in small cavities beneath the soil, known as hibernacula, where they can be inadvertently crushed by too much human activity. It’s much better to wait until the queens have emerged from dormancy and have begun to forage for sufficient nectar and pollen to start their own colonies; this way, a steady supply of pollinators will ensue. Many other species of native bees overwinter in in the dried-out hollow stalks of herbaceous annuals and perennials. Cutting and removing the stalks effectively removes the next generation from the landscape.

This is not to say that clearing, mowing or other tidying isn’t necessary or desirable—it’s merely a question of timing. The Piedmont Prairie is cut back throughout the growing season, to mimic grazing, and the plant material is left in the prairie. In some years, we work with the N.C. Forest Service on a controlled burn in later winter/early spring, in order to keep certain aggressive plants from dominating and woody shrubs and trees from taking root and shading out the perennials.

By waiting until spring for the first cleanup in your own gardens, it’s possible to have both a beautiful landscape and a thriving ecological community—a winning situation for everyone. Best of all, it involves sitting back and doing nothing in the colder months, offering us the opportunity to relax and enjoy the dormant season before leaping back into activity with the spring.

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close-up of a bumblebee nest among low growing plants in winter

Photos from top: Dried flower stalks of native wildflowers in the Piedmont Prairie, by William Hanley; bumblebee nest by Krasowit/Shutterstock.