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Do we really have to let dandelions grow?

Do we really have to let dandelions grow?
Credit: Espace pour la vie/Lise Servant
Do we really have to let dandelions grow?
  • Do we really have to let dandelions grow?
  • For some scientists, the pollen supplied by dandelions is not of optimal quality for North America’s native pollinators.
  • Red maple (Acer rubrum), a species native to Canada, blooms early in the spring and provides an excellent source of nectar and pollen for pollinators.
Do we really have to let dandelions grow?

Dandelions have been making a major comeback in recent years.

After a long period of being snubbed, the common dandelion (Taraxacum officinale) now symbolizes nature in our lawns. Although the plant has the reputation of being invasive, many virtues are attributed to it: both edible and medicinal, it blooms early and attracts pollinators at a point in time when our gardens are not yet fully in flower. Add to that the pleasure we get from making a wish when we blow on its tufted parachute-shaped fruits called a pappus.

Let’s face it, the dandelion has everything it takes to become the standard bearer of a movement advocating that we let our lawns grow freely in the spring. The simplified concept is as follows: let’s allow dandelions to bloom, and their flowers will feed the pollinators that we want to protect.

It seems like a good idea, but what’s the real story?

The two sides of the coin

I suggest we revisit the three main arguments that encourage us to mow our lawn less in the spring, but bringing some important nuances to bear.

1. Mowing less allows us to sustain biodiversity

The majority of lawns are made up of grasses like Kentucky bluegrass. Which incidentally is the most cultivated ornamental plant in Canada. Easy on the feet and esthetically pleasing, it’s sometimes sprayed with herbicides (even though regulations are evolving) in order to eliminate any form of competition from other plants and thus create a perfect, uniform lawn.

For many, any other plant growing there is considered a weed. And yet, it’s reasonable to believe that the presence of a variety of flowers should contribute to providing local biodiversity with accommodation and food. We can think of white clover, common self-heal or wild strawberries to increase the ecological value of our grassy land. This new habitat, which has something in common with a prairie, may also shelter predatory insects that in turn consume insect pests. It’s a small-scale ecosystem.

That said, in a number of zones of North America, an unwanted visitor may hide in the tall grass: the black-legged tick. If that tick is infected by a parasite, it can transmit Lyme disease. And May is incidentally Lyme Disease Awareness Month. It’s a serious health issue to be considered for the land that we visit, especially outside urban centers, where incidence rates are higher.

2. Mowing the lawn less allows for savings at a number of levels

The idea of going without mowing in the spring seems simple. For a municipality, that can mean, notably, fewer workers to pay. On top of that, knowing as we do that most mowers still have gasoline engines (sometimes high-polluting), mowing less could have an important impact on air quality. The problem is that afterwards cutting an area with longer grass can prove to be difficult, even impossible, with a traditional mower. And the piles of cut grass have to be removed so as not to smother the lawn underneath.

Finally, the lack of mowing will allow many plants to go to seed and spread, and some could end up dominating the lawn, which would then become less diversified. This doesn’t take into account the allergenic pollen of certain grasses, which is normally limited by mowing.

In short, you have to expect that important work will have to be carried out later in the season.

3. Dandelions, a valuable food source

While few flowers are available in the month of May, many grassy areas are brimming with yellow blooms. For a few years we’ve been encouraged to keep them on the basis that a valuable source of food (pollen and nectar) is involved, and for the very reason that it’s one of the only flowers at this time.

However, browsing in the scientific literature we find studies1 that contest that claim. Without drawing any conclusion, it seems reasonable to think about these issues. For some scientists, the pollen supplied by dandelions is not of optimal quality for North America’s native pollinators. Part of the explanation could come from the fact that Taraxacum officinale (the most common species) originates in Eurasia and that insects native to our regions have co-evolved with local plant species. Another study even suggests2 that the dandelion frees allelopathic substances in the soil, which inhibits the growth of other plants, thereby reducing the diversity of our lawns.

So what are the lessons to be learned?

Just don’t take things too far

The important thing to remember is not to let the lawn grow without limits, even less that dandelions, by themselves, will save bee populations. In fact, the important thing, in our opinion, is the following: when uses allow, maintenance practices must be revised in order to develop the “pollinator reflex” (2022-2027 Montréal: A Biodiversity Territory to Support the Protection of Pollinators plan). We’re talking here among other things about differentiated management, which consists in practicing maintenance adapted to green spaces according to their characteristics and their uses.3 For a residential lawn, it could involve delaying the initial springtime mowing in order to let the first dandelions flower, and avoiding very short cutting later on.

Some fields are spaces that are needed for practicing outdoor activities. Do they need to be kept as monocultures? The answer is obviously no. But if their maintenance is neglected, serious issues could arise.

As far as purely ornamental lawns are concerned, the possibility of creating diversified habitats that meet the needs of several living beings should be considered. One of the solutions is to replace unused lawns with gardens containing a number of native plants.

Although the dandelion may be an excellent standard bearer, our pollinators need more than a lawn adorned with those yellow flowers in order to return to our communities. Some trees like the red maple (Acer rubrum) bloom early in the spring and provide an excellent source of nectar and pollen for pollinators. Many other native plants also flower very early, so why not incorporate them into your land?

By taking part in the My Space for Life Garden program, you could place your green spaces at the service of biodiversity.

Legend:

1 https://academic.oup.com/jee/article/63/1/215/798721

2 http://gilbert.eeb.utoronto.ca/gilbert/files/2015/12/Loughnan-et-al.-2014-pollen-allelopathy.pdf?fbclid=IwAR2t1I_5Us_r0l-mGPFXOBGfEN5hg_qaNHXLzRiGE3sSdl1Key1DViWsF1E

3 Differentiated management in Rosemont–La Petite-Patrie (In French)

To learn more:

The impact of lawnmowers (in French)

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1 Comment(s)
James Woods's picture
James Woods

Not only am I an slice master game enthusiast, I also love flowers and trees.

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