June 2, 2023
By Lorraine Johnson and Sheila Colla

The article on No Mow May, by Dr. Sara Stricker and Dr. Eric Lyons from the Guelph Turfgrass Institute, includes a number of assertions that call out for critique. While the authors correctly point out that No Mow May is hardly a panacea for pollinators, holding up manicured turf for its ecological and human health benefits, as the authors do, is equally problematic.

They label the vegetation that grows in unmown lawn “undesirable weeds.” Included in their list of “undesirable weeds” is wild violet, a host plant for fritillary butterflies, numerous species of moths, and a pollen-specialist bee. We would suggest that it is precisely such arbitrary, aesthetic conventions of plants considered “weeds” that adherents of No Mow May are questioning — and that we need to question in the context of biodiversity and support for pollinators.

The article claims that mice and rats “love an unmown lawn” and will “sneak into your home” and “cause excessive damage to buildings” and “carry disease and fleas.” Such scare-mongering ignores the fact that the primary attractant for rats is human garbage and food waste. Rats don’t eat plants, whether they’re “tall grass and weeds” or not. They will run along densely vegetated fencelines, but if you have a rat problem this can easily be controlled by removing all garbage and food waste and maintaining a narrow strip of low vegetation along the fence.

The authors then raise the spectre of “biting insects” (“fleas, ticks and mosquitoes”) and their negative effects on human health (as disease carriers) if grass is left unmown. More scare-mongering. Mosquitoes breed in standing water. You can have a perfectly manicured lawn and still have an “infestation” of mosquitoes if you don’t remove all standing water from eavestroughs, catch basins, tubs, etc.

As for the risk of West Nile Virus from mosquitoes, research by Matthew Waltner-Toews and David Waltner-Toews (published in LA+ Interdisciplinary Journal of Landscape Architecture, Fall 2017) suggests that “lawns can also increase WNV risk” and that “planting native vegetation and attempting to create a complex, biodiverse urban ecosystem would likely reduce mosquito-borne risk by encouraging more mosquito predators.”

Ticks are indeed a human health concern, but instead of promoting manicured monocultural turfgrass for tick control, one could examine the research finding that biodiversity may reduce the risk of human exposure to Lyme disease (Ostfeld and Keesing, 2000). The research supports biodiversity for human health, not more monocultural, manicured lawns.

The authors note, correctly, the extensive research on the mental health benefits of “greenspace.” They don’t acknowledge that unmown turf is also greenspace, nor do they mention the study that compared lawns to other greenspace in the school environment and found that lawns had a negative effect on students’ academic performance (Byoung-Sun Kweon et al, 2017).

The authors are correct in stating that “when it comes to feeding pollinators, diversity is key.” But their scare-mongering continues when they label ground-nesting bees “unwanted insects.” Roughly 70 percent of bee species in Ontario are ground-nesting, and far from being “unwanted insects” they’re crucial to the pollination of wild flowering plants as well as fruit and vegetable gardens. Mown turf, which isn’t allowed to flower and thus offers no pollen or nectar for pollinators, contributes little to biodiversity and is a pollinator dead end.

The advice provided by the authors on maintaining a “healthy” lawn is sound, but what we need to do is to question a notion of health that excludes the health of pollinators and the biodiversity on which all ecosystems — and therefore human health — depend.

When the authors do mention biodiverse habitat gardens such as prairies and savannahs, they suggest relegating them to the backyard and keeping kids out. Their implication that habitat gardens should be hidden away is mired in anti-ecological aesthetics and scare-mongering about health and safety.

It’s interesting to note that what the authors list as their “perhaps more serious issue” with No Mow May is that it “could lead to homeowners giving up on their lawns entirely.” To that, we say, great, it’s a start! Turfgrass is the largest single irrigated crop in North America — a monoculture that consumes 40 million acres (roughly the size of New England) of the U.S. alone (Milesi et al, 2005) and contributes little in the way of ecological benefits (unless compared with non-porous concrete).

In the midst of a biodiversity crisis and climate emergency, what we need is an urgent rethink of landscaping conventions. What the authors have offered, instead, is a backwards-looking defence of precisely the conventions (mown turf, removing dead leaves and plant stalks, etc.) that have contributed to the mess we’re in. It’s this mess we need to weed out. And to do that important work at the local scale, the evidence is clear: we need more habitat gardens and less lawn.

Lorraine Johnson and Sheila Colla are co-authors of A Garden for the Rusty-Patched Bumblebee. Their article on No Mow May can be found in the Spring 2023 issue of ON Nature magazine, https://view.publitas.com/on-nature/spring-2023/page/38