• More people are allowing their lawns to grow wild in order to increase the range of plants and animals living in them.
  • Cutting lawns at different heights and varying the frequency of mowing can create a mix of conditions that benefit a wide range of species, an ecologist says.
  • The expert also suggests mowing less during the summer to create diverse plant and insect communities in the warmest months, but cutting grass short in autumn to foster conditions for mushrooms.

Alongside the worrying current fad for plastic grass, a growing number of people are choosing to let their lawns grow wild in order to encourage a more diverse range of plants and insects to live in them.

You may not be convinced of the beauty of a wild and unruly garden, but there is a sweet spot to be found between a rewilded jungle and a sterile green desert which not only looks good but provides a haven for wildlife. This is especially important in the UK, where 97% of semi-natural grassland has been destroyed over the last 80 years.

I’m an ecologist specialised in the study of this kind of habitat, and I want to help you get the most out of it. One simple compromise you can make is to put off when you first get the lawn mower out each year. A campaign by conservation charity Plantlife called #NoMowMay asks people with lawns to hold off the first cut until June, which allows grasses and herbs time to flower and set seed.

But if you want to maintain a wildlife-friendly lawn throughout the year, without letting your garden become completely overgrown, here’s some advice for what else you can do.

To find a happy medium, some mowing may be necessary. This halts the ecological processes which would otherwise transform a grass lawn into a woodland over time. By varying the height at which you mow different areas of your lawn and how often you do it (simulating the effect of different herbivores grazing in the wild), you can create a mix of conditions which benefit a variety of species.

Areas cut short will favour daisies, which flower in profusion and offer a nectar buffet to bees and butterflies. Unkempt areas left uncut for a year suit a wider variety of flowers, tempting a diverse cast of bugs and other creatures into your garden.

A close view of wasps on top of a lawn
Flowers can encourage a range of biodiversity into our gardens
Image: Unsplash/Franz Michael Schneeberger

In experiments on his own garden in Kent, Charles Darwin recorded that refraining from mowing turf for too long resulted in fewer species overall, because: "the more vigorous plants gradually kill the less vigorous … thus out of 20 species growing on a little plot of turf (three feet by four) nine species perished from the other species being allowed to grow up freely."

Another key thing to think about is the level of nutrients the lawn receives. Even if you have never succumbed to the lawn feed products heavily promoted in most garden centres, your lawn will get a sufficient dose of fertiliser from reactive nitrogen carried on the wind.

The purpose of mowing in a natural grassland should be to mimic grazing by animals. And to do that, you have to remove the clippings otherwise the nutrients they carry will soak back into the soil.

Fungi and bacteria decompose dead plant material and return those nutrients to plants in a lawn through networks of mycorrhizal fungi in the soil. Regular mows which dump the cuttings and overload the soil with nutrients drive a stick through the spokes of this cycle by devaluing the currency of the nitrogen and phosphorus fungi deliver. Clumps of cut grass can also smother small seedlings.

At unnaturally high soil nutrient levels (common in lawns mown and topped with the clippings regularly), the vegetation is dominated by a small number of fast-growing, weedy species. As Darwin found, this prevents a rich community of wildflowers from taking shape. Soil with low nutrient levels favours not only more species, but also healthy soil food webs.

At the Rothamsted Park Grass experiment in Hertfordshire, scientists have studied the effects of annual haycutting since 1860, making it the oldest field experiment in the world. When fertiliser was evenly applied to some plots, it reduced the number of plant species from 40 to fewer than five.

A close view of a lawn mower cutting grass
Grass cuttings inundate soils with more nutrients than a diverse community of plants needs.
Image: Unsplash/Daniel Watson

Autumn fruiting

You also want to consider the time of year. Mow sparingly and leave grass long in summer to create diverse plant and insect communities in the warmest months. A lawn left uncut until late July, as in a traditional hay meadow, will favour the greatest variety of flowers. But cut it short in autumn to foster conditions for mushrooms fruiting as the year winds down.

Soil organisms and their hidden lives are badly neglected in nature conservation. Among the most overlooked are grassland macrofungi, so named because they are large enough to be visible to the naked eye. My favourites are the brightly coloured waxcaps. These film stars of the fungal world are restricted to undisturbed grasslands where soil nutrient concentrations are low.

The British Isles is a global hotspot for these fungi, but they are threatened by habitat loss. 11 species found in the UK were assessed by international experts as vulnerable – the same extinction risk faced by the panda and snow leopard.

Pink ballerina mushrooms in an Aberystwyth garden.
Pink ballerina mushrooms in an Aberystwyth garden. This species is considered globally vulnerable by the International Union for the Conservation of Nature (IUCN).
Image: The Conversation/Gareth Griffith, Author provided

A study by my research group showed that waxcaps need the turf to be short (8cm tall at most) in the autumn, but that their most prolific fruiting occurred when the grass was left uncut until mid-July. Waxcaps grow slowly and are long-lived, but with late cuts and the removal of clippings to lower soil nutrient levels, it is likely that the first waxcaps will return within a decade.

To sum up, delay mowing until midsummer, keep your lawn free of clippings and leave patches more unkempt for longer to please butterflies and bees. But give it regular trims from August onwards to encourage globally rare mushrooms. You’ll then see that grasslands are diverse and dynamic habitats just waiting to be unleashed.

Nature

What is the World Economic Forum doing about nature?

Biodiversity loss and climate change are occurring at unprecedented rates, threatening humanity’s very survival. Nature is in crisis, but there is hope. Investing in nature can not only increase our resilience to socioeconomic and environmental shocks, but it can help societies thrive.

There is strong recognition within the Forum that the future must be net-zero and nature-positive. The Nature Action Agenda initiative, within the Platform for Accelerating Nature-based Solutions, is an inclusive, multistakeholder movement catalysing economic action to halt biodiversity loss by 2030.

Dynamic and flourishing natural ecosystems are the foundation for human wellbeing and prosperity. The Future of Nature and Business report found that nature-positive transitions in key sectors are good for the economy and could generate up to $10.1 trillion in annual business value and create 395 million jobs by 2030.

To support these transitions, the Platform for Accelerating Nature-based Solutions has convened a community of Champions for Nature promoting the sustainable management of the planet for the good of the economy and society. The Nature Action Agenda also recently launched the 100 Million Farmers initiative, which will drive the transition of the food and agriculture system towards a regenerative model, as well as the BiodiverCities by 2030 initiative to create an urban development model that is in harmony with nature.

Get in touch if you would like to collaborate on these efforts or join one of our communities.