By Jessica Harvey, CSU Extension – Denver Master Gardener since 2020
As we wrap up the season and put our gardens to bed, there are a number of ways we can help provide habitat for our pollinators in the process. Many pollinators will nest in the hollow of stems or wood. Others will use things like leaves, mud, plant hairs, and resin to build their nests for the winter. Rather than chopping everything down and clearing out the remaining debris, let’s consider whether any of it may be used by a pollinator this winter, or even next spring.
For those pollinators that like to nest within hollow stems, consider deadheading rather than chopping those stems down to their base. Stems can range 8 to 24 inches long, from both flowers and grasses alike, to be of use for cavity nesters. A nest within a hollow stem will typically house eggs, a food source and a natural plug of some kind that can be specific to the type of pollinator that are nesting within. A couple of great examples are leaf cutter bees (Megachile) and Mason bees (Osmia and/or Hoplitis).
Remember to allow those same stems to decay and fall on their own in the spring as you don’t want to remove them until after the young have emerged for the season. If you grow raspberries doing so is easy, since you may need those prime canes for next year’s production.
Check out this great handout with diagrams highlighting some of the different cavity nesters from University of Minnesota Extension and their Bee Lab.
Not to be forgotten, consider pollinators that are ground nesters as well. It’s important to leave some bare earth for these guys to burrow into for their nests. If you have pets or children, you may consider a place out of the way within your garden.
Another excellent resource is CSU Fact Sheet No 5.615 Attracting Native Bees to your Landscape which provides more information on different nesting materials and ways you can provide additional habitat specifically for native bees.
Just like any other living thing, the main concerns for pollinators are food, water, and shelter. As we clean up and leave some debris intact for them as shelter, it’s also important to try to provide some clean water. It may be hard to do this during the winter but consider adding a tray with pebbles near your hollow stems or bare ground, and keep it topped off during the fall and spring. No need to buy anything specifically marketed as such, it can be as simple as the drip tray from a container you aren’t using.
As we wrap up for the season and begin planning for the next, also consider whether you have a year-round source of both pollen and/or nectar within your garden to encourage a strong pollinator population. Ground covers, winter blooming crocus and early blooming grape hyacinths (Muscari) will help to bridge some of the gaps.
CSU Factsheet 5.616 Creating Pollinator Habitat gives a glimpse of all the things to consider as you plan your garden as a pollinator habitat, including some plants to consider for all season provisions.
It’s important to remember our pollinators not just during the peak of the season when we need them for our flower, fruit, or vegetable production. They provide so much for us and we need to try and return the favor wherever we can.