Mow your lawn less to save bees, say scientists


It is the perfect excuse to ignore the nagging and put off mowing the lawn for a little bit longer.  

New research has revealed that leaving a fortnight’s gap between trims rather than mowing every week helps to grow more of the pollinating plants that bees need to survive.

But cutting the grass less often – once every three weeks – is also less effective than the fortnightly mow, said US ecologists who carried out the research.

This may be because longer grass blocks access to low-standing lawn flowers popular with the insects such as dandelions and clover.

Researchers mowed 16 residential lawns in Springfield, Massachusetts, over two years to discover how much bees relied on back gardens for survival.

Lead author Dr Susannah Lerman, an ecologist at the University of Massachusetts, said: ‘Bees and other pollinators provide essential ecosystem services in agricultural and natural landscapes, and they are experiencing severe declines on a global scale.

‘We found that backyards can be a surprisingly beneficial habitat for bees.

‘Mowing less frequently can improve pollinator habitat and can be a practical, economical, and time-saving alternative to lawn replacement or even planting pollinator gardens.’

The team assigned each of the study’s 16 suburban backyards one of three mowing schedules.

Gardens were mowed either weekly, fortnightly, or every three weeks, and then tested how bees responded by identifying and counting the insects.

Before each of five bee-sampling sessions per season scientists counted ‘lawn flowers’ such as clover and dandelions growing within the grass of each property.

Lawn flowers have previously been shown to encourage a greater number and diversity of pollinating insects to gardens all over the world. 

In the new study, scientists found the number of bee species and the abundance of lawn flowers were up to 2.5 times higher when researchers mowed lawns fortnightly.

Cutting the grass more often than this destroys dandelions and clover which the insects need for pollen, researchers said. 

While the diversity of bee species was highest in gardens mowed every three weeks, the average number of bees was lower than lawns cut every two weeks.

This may be because lawn flowers in backyards cut fortnightly have shorter grass, providing easier access to low-lying lawn flowers, researcher said.

Bees are vital to the survival of mankind as they are responsible for cross pollination that helps plants and crops to grow all over the world.

But across the globe, native species have been mysteriously dying out with experts blaming it on everything from pesticides to climate change.

Loss of natural habitat is a key problem and backyards and gardens are an ideal replacement because they have a variety of plants, are normally pesticide free and are widespread across the planet.

Dr Lerman, who also works for the US Department of Agriculture, said: ‘Mowing less frequently is practical, economical and a timesaving alternative to replacing lawns or even planting pollinator gardens.’ 

Guy Barter, chief horticulturalist at the Royal Horticultural Society, said: ‘Bees will visit lawn flowers including daisies, and some lawn weeds such as clover are also good bee fodder, as well as staying green during times of drought.

‘This is a good reason to spare these flowers in all but the finest turf.

‘In Britain we favour leaving areas of lawns un-mown for the summer.

‘Where this is not possible raising the mowing height will allow some wild plants to flower, especially in hot weather, and importantly without unacceptable reduction in quality of the average domestic lawn.’



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