Advocates for No Mow May say that not mowing during this month helps insects—that protecting the flowers of plants growing in our grass means more pollen available to bees, butterflies, and other six-legged critters. But is this actually true?

It turns out that most non-grass plants in city lawns are not native—and some are actually invasive, including dandelions, the primary beneficiary of No Mow May. In fact, dandelion pollen is generally less nutritious than the pollen of native plant flowers, so leaving thousands of dandelions unmowed in May is like opening a McDonald’s on every corner.

“But bees have nothing to eat in spring without dandelions!”

Not true. Many native plants bloom in spring, including trees (for example, maples and birches), shrubs (like pussy willow and red-osier dogwood), and wildflowers (spring beauty, Dutchman’s breeches, trillium, trout lily, bloodroot, marsh marigold, others).

And remember, our native critters have endured here in Ontario for hundreds of thousands to millions of years without dandelions. They do not need them.

Dandelions can suppress native plants

Another down side of dandelions is they can bully native plants. A University of Toronto study found that dandelion pollen to be allelopathic. In other words, when their pollen ended up on a native plant, the latter’s reproductive success fell. Their roots have also been found to be allelopathic. Here’s what one management guide has to say about dandelions:

Dandelion has many characteristics that contribute to its success as an invader. It thrives in almost any climatic and soil conditions, reproduces prolifically, and regenerates easily. Dandelion’s long root system extends beyond those of neighboring plants, conferring it an advantage in nutrient and water uptake. Dandelion performs some level of allelopathy, inhibiting the growth or germination of native
plants, and also produces compounds with antifungal properties. Through its almost-total inhibition of native plants, Dandelion severely degrades the quality of the habitats in which it becomes established.

Instead of No-Mow May, how about More-Natives May?

So instead of No Mow May, how about More Natives May?  Instead of focusing on protecting lawn weeds, consider reducing the size of your lawn and planting native plants—the species our native insects and other wild creatures are adapted to. See the Sault/Algoma Grow Me Instead Guide for native plant recommendations.

Still not convinced?

If you feel strongly that you do not want to mow your lawn in May, that’s your choice. Any reduction in lawnmower-related emissions helps fight climate change, and you may leave tiny critters living in your lawn feeling less stressed for a month.

But do it knowing that most of the flowers you are protecting are not native so do not provide the best food for native pollinators.

Questions?

Email us at info@cleannorth.org.

Reading list

• Saving our bees by Heather Holm
• Early spring blooming plants (and why dandelions are not a good food source for bees)
• My yearly dandelion spring rant!
• No Mow May could backfire: Here’s why
• Taraxacum officinale pollen depresses seed set of montane wildflowers through pollen allelopathy
• Best management practices: Dandelion