Let Dead Plant Material Lie

Photo and article by Plant NOVA Natives

Our splendid native plants are going dormant for the winter and leaving behind their seed heads and dead stalks as a reminder of growing season glory. Many of us are inclined to perceive these remnants as unsightly “garden debris” that should be cut and cleared sooner rather than later. Better now than in the spring, right?

Wrong! Dead native plant material is integral to a healthy ecosystem. An essential support for the populations of pollinators and other animals upon which we all depend, nothing comes close to replacing its role in the health of a diverse ecosystem. Before trotting out the clippers and rakes, consider this:

Dead stalks: Many dead stalks of native plants contain hollow spaces that are like 5-star winter resorts for the insect world. We may frown at their appearance, but native bees, among others, are industriously and ingeniously taking advantage of them in surprising ways. Adorable little bees that are so tiny you may never have noticed them are laying eggs, hibernating, and otherwise snuggling down for the harsh winter in the stem shelter of the native plants we installed. Insects aren’t the only critters who profit. Dead plant material provides shelter and nesting resources for birds and many others.

Dead leaves: Butterflies can spend the winter in leaf litter as caterpillars and chrysalises. The Mourning Cloak, Question Mark, and Comma butterflies, for example, overwinter in dead leaves as adults after entering a dormant phase called “diapause.” Moth species such as Luna Moth and Isabella Tiger Moth also pupate in leaf litter. Salamanders, some turtles and other creatures find shelter there as well.

Seeds and berries: Seeds on flowerheads and winter berries are an important source of nourishment for both resident and migrating birds and are consumed throughout the fall and winter. Living or dead, native plant material has immense value for wildlife.

Living soil: Dead and decomposing plant material are valuable components of soil. Gardeners and landscapers spend considerable time and money on store-bought organic material to condition the clay soil often encountered in Northern Virginia. But the decomposing plant material already present helps build humus, a dark organic material comprised of approximately 60% carbon, 6% nitrogen, and small amounts of phosphorus and sulfur. Humus-rich soil encourages a proliferation of beneficial soil organisms and microorganisms. It also holds moisture and retains soil structure for better air and water circulation. The decomposition process creates very fertile ground indeed for native plant gardening.

Armed with this expanded understanding, it seems that the best fall cleanup strategy is to not have one: leave the stalks, stems and leaves alone and let them lie, right where they are, over the winter. A light cleanup or pruning in early spring to encourage new growth can be done with little or no harm to local wildlife. More information on garden and landscape maintenance can be found on the Plant NOVA Natives website.

We would be remiss not to include a word here about gardening aesthetics. We humans care about how things look. In daily life, surrounded by people, garden beauty and aesthetics will always be a consideration. Our definition of “garden beauty,” however, can certainly evolve. Are not waving seedheads more interesting than bare ground? And is it not beautiful that all kinds of animals need our pollinator gardens for more than just pollen? That our efforts not only attract pollinators but enable their very survival? That it takes just a bit of forbearance to advance and strengthen the biodiversity of the region?

Let’s pause the garden cleanup until spring, and then be gentle on the emerging life.