Grasshopper bug B and B in the Pollinator Garden at the National Museum of Natural History

As we pack away the holiday decorations and look around our cold and frosty gardens, the traditional custom is to clean everything up. Well, consider this your official permission to procrastinate that winter cleanup! If you are dreading the doldrums of winter and are not looking forward to raking up all those leaves and cutting back all those dormant perennials, you are in luck! Not only can you relax and enjoy the ‘bones’ of your garden and ‘architecture’ of dormant shrubs and perennials, but you can be confident that you are allowing native pollinators and other wildlife to enjoy cozy overwintering sites.

Many conservation and wildlife organizations encourage gardeners to refrain from all that cleanup and to “Leave the Leaves” to support pollinators. Leaving organic ground litter (leaves, stalks, stems, etc.) in place adds useful nutrients for plant health as it decomposes, buffers the intensity of freeze/thaw cycles, helps retain moisture, suppresses weeds, and provides nesting materials for a wide variety of invertebrates. According to the Xerces Society for Invertebrate Conservation, “The availability of nesting and overwintering habitat is one of the most important factors influencing populations of native bees and other beneficial insects.” For example the Clemson Cooperative Extension explains that, “Fireflies, who are beetles, live the bulk of their lives (95%) as larva in leaf litter, under rotting logs, and in moist areas where they can thrive.” Can you image a summer’s night without fireflies!?

1. Leave your leaves in place when you can.

  • It is ok to rake leaves out of your lawn and keep pathways clear, but leaving them in your garden beds and under trees and shrubs helps a lot. If you need to remove leaves, consider moving them to a pile in a back corner of your garden or compost pile.
  • Pro tip: Rake all the leaves onto a tarp and drag the contents to their final destination instead of bagging to save time and energy.
Leaf litter at the Bird Garden at the National Museum of Natural History

Leaf litter around Hellebores and Heuchera in the Urban Bird Garden at the National Museum of Natural History.

2. Leave stalks, seed heads, and stems in place until spring.

  • Indicators for cutback time: when you start to see pollinators flying around and temperatures are consistently around 50˚ F.
  • If the aesthetics of leaving up those plant stalks bother you, consider a few alternatives.

o Cut back perennials to the base of the plant once dormant and stash that green waste in a back corner of your garden. Later incorporate into your compost pile.

o Cut stalks down to between 8-24 inches from the base of the plant. This createsvertical nesting sites with a range of diameters and heights to suit a variety of insects. Move excess debris to a back corner of the garden.

  • Pro tip: My favorite approach is to cut down the plants but leave the stalks on the ground in sections longer than 8 inches (the longer the better). With a 6-foot-long stalk, for example, cut at 4 feet above the ground, at 2 feet, and lastly at the base. There is nothing to haul away and you get free mulch.
Echinacea seed heads (coneflower) in the Pollinator Garden at the National Museum of Natural History
Joe Pye stalks in the Pollinator Garden at the National Museum of Natural History

Seed heads of Echinacea (Coneflower) and Eutrochium (Joe Pye Weed) National Museum of Natural History are left standing in our gardens for insects to use as nesting sites.

3. Let Logs Lie

  • Let dead trees stay in place if they are not a safety hazard; this creates a “snag” which supports myriad wildlife including insects, woodpeckers, owls, skinks, and lizards.
  • If a dead tree poses an issue, cut it down and deposit it on site in the back of a bed or garden.
  • Pro tip: Have some leftover logs, twigs, or stumps that you do not want to have to haul away? Consider using them to create visually interesting insect ‘hotels’ (or Bug B&Bs). Several of these are featured around the Smithsonian’s Washington, D.C. campus.
Log wall at the Pollinator Garden at the National Museum of Natural History
A wall filled with natural materials in the Mary Livingston Ripley Garden provide plenty of nooks and crannies for wildlife to find shelter.

A log wall in the Pollinator Garden at the National Museum of Natural History and a wall filled with natural materials in the Mary Livingston Ripley Garden provide plenty of nooks and crannies for wildlife to find shelter.

4. Allow for bare ground, dry stacked rocks, brush piles, and clean water sources.

  • Many pollinators are non-aggressive, often solitary, ground dwellers meaning they can utilize bare soil to make their nests.
  • Rocks and brush piles, either naturally occurring or artfully installed in the garden, provide crevices for wildlife in which to live.
  • Allowing for shallow, mosquito-free puddles or a water-filled dish (bumblebee bath, anyone?) for reliable, clean drinking water is another way to help to wildlife.
A shallow bird bath provides a valuable source of water through the winter in the Pollinator Garden at the National Museum of Natural History.
Ground nest bees in the Pollinator Garden at the National Museum of Natural History

A shallow bird bath provides a valuable source of water through the winter, while bare ground provides a spot for native, ground-dwelling bees to make a nest in.

By pausing to consider how wildlife uses your garden spaces and by gardening thoughtfully and purposefully, we can all contribute to the overall health and numbers of beneficial insects and other wildlife. Helping them translates to our gardens being enriched to produce beautiful blossoms to enjoy and diverse bounties of vegetables, fruits, and herbs to incorporate in our diets. Take a break this winter, LEAVE THE LEAVES, grab a warm drink, and cozy up to those plant and seed catalogs (you can never have too many plants) you’ve been looking forward to perusing!