North American gardeners use a lot of mulch. We’re told that it is the best way to suppress weeds and prevent soil from drying out. Plus it looks very tidy.
However, mulch is bad news for native bees. Approximately 70% of native bees nest in the ground; they dig nest tunnels in areas of bare ground or between plants. These native bees cannot dig through wood mulch. Well, what is a pollinator gardener to do, then?
Right plant, right place
Choose the right plant for the right place. If you have dry, sandy soil, choose plants that thrive in those conditions. This way, you won’t have to worry about watering them constantly to keep them alive. There are lots of native plants that will grow in dry conditions. For ideas, check the Wildflower Farm seed mix components in their “Claybuster! Seed Mix” and “Dry, Sandy Soil Mix”.
Use composted mulch sparingly
I do still use some mulch around newly planted flowers and seedlings while they are establishing their root systems. This is the most vulnerable time for new plants. I place a 2-inch high ring of mulch around each plant to prevent the new, short roots from drying out. This ring also prevents water from running off away from the plant if I need to hand-water. Keep the mulch from touching the base of the plant so the stems don’t rot.
Also choose a type of mulch that will break down easily within a year or so. I use composted leaves that I gather from our lawn and pile up in a back corner of the yard. When I buy mulch, I use composted pine mulch from Greely Sand and Gravel. The composted pine mulch is dark brown, doesn’t fade, isn’t dyed, and has a soft, fine texture. I buy truck loads that are dumped in our driveway, but you can also buy it in re-usable bags that keep the mulch contained.
I use most of this mulch for paths. I layer newspapers along the routes and then cover them with composted pine mulch.
Use ‘living’ mulch
Recently, I’ve begun using ‘living’ mulch. Here, you use low-growing, ground-cover plants that spread and weave between taller ones. They help protect the soil from drying out, out-compete and suppress many weeds, and reduce erosion. Ground-cover plants still allow bees to dig nests. I first came across this idea in the book Planting in a Post-wild World by Thomas Rainer and Claudia West, at the Ottawa Public Library. The authors encourage layering plants within a garden — plants with different heights and types of root systems share the same area, but perform different roles. Tall plants provide structure, medium-height plants provide visual interest with flowers and texture, ground-hugging plants protect the soil, and filler-plants cover up gaps between the other layers. Listen to Margaret Roach’s interviews with Thomas Rainer and Claudia West on the A Way to Garden podcast.
In sunny areas, I am experimenting with wild strawberry and field pussytoes as native ground covers. My favourite non-native one is sedums because bees like the flowers too. For shade, I’m using violets, barren strawberry, foam flower, sedges, wild ginger, and common self-heal.
Also avoid landscape fabric
Obviously, ground-nesting bees cannot dig through landscape fabric either.
I have had thoroughly unsuccessful and unpleasant experiences with landscape fabric anyway. While landscape fabric does work temporarily when a garden is first installed, weeds will gradually grow into the fabric making it difficult to remove the weeds or the fabric. If you use thin, cheap landscape fabric it takes forever to rip it out one tiny piece at a time. When I removed thick, felted landscape fabric, it resembled a long, green shag carpet from the 70’s with weeds fused to the fabric. I have vowed to never use landscape fabric again.