No Mow May is a bad idea for Canadian lawns according to the University of Guelph and the Guelph Turfgrass Institute.
Most weeds such as dandelions supply insufficient nutrition to the pollinators. Trees in the apple, willow and rose family produce more nutritious pollen that weeds found in lawns. Another problem is that the insects can become reliant on that one location to find food and then, all a sudden it’s gone.
Allowing lawns to grow excessively creates temporary habitat. This isn’t helpful to pollinators when the grass is eventually mowed.
No Mow May can harm your lawn. It encourages undesirable weed species like thistles, knotweed and wild violet which can be challenging to remove. Also, cutting too much grass length at once, leaves it vulnerable to insects, weeds and disease.
So, please mow your lawns. You can create wildflower zones in your garden to benefit insects year round. A more thoughtful approach is needed to benefit pollinators. Do some research. The University of Guelph is a good source.
Betty Eadie, Cornwall