At the time that Greenbelt first promoted “No-Mow April” in 2022, this garden writer, Master Gardener and lifelong gardener wrote “Beware No-Mow April” about its potential harm to turfgrass, citing U.Maryland lawn-care advice. Even if you’re anti-lawn, the most environmentally responsible kind of lawn is a thick, healthy one that prevents stormwater run-off and weeds while requiring no treatments of any kind.

Since then, reviews by experts of the No-Mow campaign have appeared and the consensus is far worse than I’d imagined. Even the nation’s leading voices for wildlife-friendly gardening criticize the campaign, while proposing changes that actually DO help pollinators. (Or course, they’re much more difficult than the simple “do nothing for a month” message.) And the one study cited by “No-Mow” proponents has been withdrawn.

I summarized the science-based reviews of No-Mow in the following letter to Greenbelt’s new City Manager Josué Salmerón, who responded quickly that it’s a matter of policy, so he’s forwarded it to the Council.

February 13, 2024

Dear City Manager Salmerón:

I’m writing about the “No-Mow April” campaign in which the City of Greenbelt participated in 2022 and 2023, to urge the city to not participate again in 2024. It’s a campaign promulgated by the Xerces Society’s Bee City program, which Greenbelt currently partners with. The city mentions it here on its website.

The stated purpose of the no-mow campaign, which asks residents to not mow during the month of April, is to help pollinating insects. But since its arrival in the U.S. from England two years ago, the reviews are in – and the campaign seems to do more harm than good. 

From top U.S. advocates for gardening for wildlife

From a spokesperson for the National Wildlife Federation (in this interview): “We’ve really been leaning into and pushing what we call Grow Beyond No-Mow May. The reason is in certain areas this might make sense but it’s not a universal approach. Many areas don’t have the kind of growing green turf season, for one thing. The other thing is that the only benefit is if the lawn has a substantial number of noninvasive wildflowers that actually benefit pollinators. If you’re just not growing monoculture turfgrass, then nothing’s really happening for the wildlife.” Podcast host: “You’re just getting longer monoculture turfgrass.” NWF: “Exactly, which sadly can attract ticks and other kinds of pests that you don’t want. So it’s not a universal solution.”

In Real Simple magazine: “Dr. Doug Tallamy [U.Delaware] sees little logic in letting lawns grow longer for a few weeks. ‘If people simply let their grass grow for a month and then revert to a clipped green monoculture, they are teasing pollinators with short-term snacks followed by starvation,’ he said.”

Benjamin Vogt in “No Mow May is Unwise:” “No mow May continues to frustrate the heck out of me. Just letting your lawn go will not result in a lovely meadow that neighbors or wildlife will admire. If you’re on an urban lot, chances are you won’t be getting aster and indigo and prairie clover and coneflowers — they aren’t in the seed bank because your house was not recently built on top of a remnant prairie. What you WILL get are a host of plants with marginal to little benefit to wildlife, and several that will be terribly aggressive: crabgrass, creeping charlie, barnyard grass. And of course invasive species placed on most city’s noxious weed list, like musk thistle or garlic mustard.”

Then for Better Homes and Gardens,Vogt summarized the reasons “Why No Mow May Isn’t Such a Great Idea:  Allows Invasive Plants to Grow, Only Temporary Support for Native Bees, Promotes Less Valuable Flowers.” He goes on to explain what changes would help pollinators.

From Iowa State’s “Tips for Participating in No-Mow May”  these headings from the page:

• It Will Take a Lot of Effort to Get the Lawn Back Under Control,
• You Will Encourage the Growth of More Weedy and Invasive Plants
• Consider an Alternative to No Mow May – Participate in Mow-Less May

The authors of a book about creating habitat posted “The Surprising Downside of #NoMowMay” in Rewilding Magazine:

There’s huge value in challenging monocultural lawns and the enormous ecological damage they have caused, but offering a feel-good moment of aesthetic rebellion risks obscuring, and even undermining, the bigger goal….A month of long lawns filled with dandelions and other non-native weedy species just doesn’t cut it. It’s the ecological equivalent of opening a fast-food restaurant on every corner – for a short amount of time. At best, burgers and fries for a while, but not a sustained full-service menu of healthy nutrition and habitat for pollinators.”  They even warn of possible harm to native wildflowers caused by the proliferation of dandelions.

More From Academia

Leaders of the science-based Garden Professors Facebook Group have weighed in:

– Dr. Linda Chalker-Scott wrote:  “I don’t believe this is a science-based recommendation, at least not plant-science based. Letting the grass grow too long is bad on lawns health and integrity. Thin or dead patches that are apparent after the top layer is mown are invitations to weed invasion. And that means homeowners are likely to use herbicides”.

– Sylvia Thompson-Hacker wrote:

“No-mow doesn’t necessarily mean more benefits to pollinators. The assumption that plants blooming in the lawn are attractive to pollinators is fallacious. But let’s assume there are plants attractive to bees in the lawn. The controlling point is the turf mix percentage, the grass : blooming forbs ratio. Not mowing and allowing them to bloom more would be a benefit to insects, that makes sense. But if the lawn is largely grass allowing it to grow long won’t provide the same profit. Plus letting grass get too long between mowings isn’t good for the grass itself…In urban situations many if not most of the blooming turf weeds aren’t native and tend to be easily spread, many by wind. Encouraging pollination can exacerbate the situation, leading to more weeds and perhaps encouraging the homeowner to resort to chemical control. And many of these nonnative turf-invading plants can be kept in check by regular mowing.”

From U.Maryland Home and Garden Information Center:

Infrequent mowing allows the turf to grow too tall. Subsequent mowing removes too much leaf surface and may shock the plants. Weekly mowing may not be enough, especially during the peak period of leaf growth in the spring. Remove no more than one-third of the grass blade each time you mow. Removing larger amounts of leaf surface may result in physiological shock to the plant, cause excessive graying or browning of leaf tips, and greatly curtail photosynthesis reducing the health of the grass.

 

The main benefit of the [no-mow-month] movement is its ability to get gardeners thinking about their landscaping choices and actions and the impacts of these on the ecosystem. (And that’s a good thing!) That said, most of the flowering lawn weeds that no-mow is supposed to protect are non-native and do not support many of our native bees, and allowing them to set seed only enables them to spread further in places where native plants should ideally be growing instead.

What about research in support of No-Mow? The popularity of the campaign took off in 2020 when a study from Lawrence University in Appleton, Wisconsin seemed to support it, but the journal that published the paper has since retracted that study – due to “shoddy scholarship.”  And in my research that’s the only study I’ve seen cited in support of no-mow.

 Elsewhere in the Media

The wire service AP News published:“Good intentions, bad approach, critics say.”

Some of those pollinators you set out to protect will likely get shredded up with the first mow of the season. Grass will no doubt get shaded by tall weeds, which can lead to fungal diseases. And weeds and invasive plants that take hold during the month won’t simply disappear once the mowing commences. That might lead people to apply chemical pesticides they wouldn’t otherwise use.

AP includes this quote from Tamson Yeh, turf specialist with the Cornell Cooperative Extension of Suffolk County in New York:

I think it’s a terrible idea, too,” she said. “It’s such a nice slogan, but letting the grass grow high and allowing it to do its thing, and then suddenly mowing it back is really counterproductive…Other problems with the practice include confusing insects when the grass is suddenly low again. That gives predators the opportunity to take advantage of them…There’s also the potential to disturb a nest of bunnies when mowing,’ she said, calling the discovery ‘the most horrible experience you can have.’

More Effective Ways to Help Pollinators are Sought

In my conversation with Mayor Pro Temp Kristen Weaver about the harmful effects of the No-Mow April, she suggested I explore ways the city could be more effective in helping pollinators, and I took seriously her call for research. One organization that the Greenbelt-Beltsville Garden Club is considering aligning with is the respected, science-based organization Pollinator Partnership. I’m one of the club members currently enrolled in its Pollinator Stewardship training, after which the club itself may apply for stewardship certification. We’re in communication with people at Pollinator Partnerships headquarters about resources for cities, as a replacement for or addition to the Bee City program that Greenbelt currently aligns with.

Respectfully, Susan Harris