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Why you should mow your lawn less often to help the planet

Our obsession with manicured, herbicide- and pesticide-controlled lawns has created green spaces “barren of beetle and bee” that contaminate groundwater and create more greenhouse gases than they soak up.

Maria Ignatieva’s world is crisping to brown. In Perth, where she works at the University of Western Australia, the mercury is climbing to a Saturday high of 40°C – the hottest November day since records began in 1897 – exacerbating conditions that are fuelling fires across much of the continent.

In the city, indigenous plants are coping with the heat. “They are designed for that,” Ignatieva says, on the phone from her downtown apartment. “That is why they don’t look lush and green.” But, to keep the naturally sandy city looking like a rain-soaked European landscape, the uniform carpets of grass are on a life-support system of precious groundwater.

As in all the cities the Russian-born landscape architect and botanist has lived in – St Petersburg, Syracuse, Uppsala in Sweden, Christchurch and now Perth – the garden, she says, “is still a big deal”. By “garden”, she means those vast expanses of private and public land covered in short-cropped, often exotic grass – a global homogenous landscape that, she says, can result in a loss of local identity and biodiversity and increases the costs of maintenance and management.

“We don’t need to cover all the leftover parts of the city with rugs of green grass. Particularly with climate change, we need to create a new urban environment that can cope with such temperatures.”arbitrary

Residents defend a property from a bush fire at Hillsville, north of Sydney. Photo/Getty Images

City planners and landscape designers, she says, have a role in promoting different planting programmes, design configurations and palettes better able to handle rising temperatures and diminishing groundwater – Ignatieva is working with the turf industry to identify such species – “but when you compare [more resilient species] with green-lawn turfs – how do you get people to accept more sustainable browns and yellows? People’s acceptance of different aesthetic patterns is the most difficult part.”

It is a near-global conundrum. Worldwide, including New Zealand, demand for pasture for grazing has been responsible for huge tracts of deforestation. As fires burn across the Amazon forest, figures from Brazil’s National Institute for Space Research show that, in July this year, the rainforest lost 2,254sq km of vegetation, fuelling fears President Jair Bolsonaro’s pro-agribusiness stance will further accelerate deforestation   and the risk of out-of-control fires. Our cities, too, are turning a uniform shade of green. Research by Ignatieva and landscape ecologist Marcus Hedblom, published in Science last year, found lawn covers about 70% of open urban spaces in modern cities worldwide – in the US, lawn grass is the largest irrigated non-food crop in that country, covering about 163,000sq km. Extrapolating their data, they say the flat green grass cloaking playgrounds, sports fields, golf courses, river banks, berms, reserves and private lawns now covers up to 800,000sq km of the world’s surface – about the size of Pakistan – including wildly inhospitable environments such as Dubai and parts of China.

New Zealand is no different. Between 15% and 20% of Auckland is grassland – that’s an estimated 150-200sq km of green. More than 70% of Christchurch’s urban green space is given over to lawn; a survey of south-western suburbs found on average just under a half of each residential property is grass.

Water bubbles up from a manhole on the flooded St Mark’s Square in Venice. Photo/Getty Images

These lawns require work. As New York Times Magazine writer Michael Pollan famously claimed, “Gardening means war.” It’s war against drought – Ignatieva’s study found households in arid regions of the US direct three-quarters of their water use to watering their lawns; even with summertime watering restrictions, Perth uses 73 billion litres of groundwater to irrigate its public green spaces each year – private homeowners pump an additional 72 billion litres of water from unlicensed backyard bores.

And it’s war against weeds and insects. Around the world, herbicides, pesticides and fertilisers are deployed to encourage the growth of a single species of grass, leaving a weirdly quiet biodiversity desert, writes British horticulturalist Alys Fowler, “barren of beetle and bee”.

Then we wrench the lawnmower into action to stem that same growth. This weekend, every weekend over summer, the hum of insects will be drowned out by the roar of thousands of lawnmowers sheering the green tips off fescue, couch grass, kikuyu, Kentucky bluegrass and rye grass; slicing off the flowering heads of clover, daisy and any native plant species that dares to get a foothold in our domestic grasslands to leave a flat, green summertime promise of picnics, outdoor entertaining, backyard cricket or just lolling on the grass with a good book. According to a recent University of Auckland survey, the majority of lawn owners mow the grass with a petrol mower every two weeks.

And why not? As well as providing space to play, relax and entertain, lawns produce oxygen, store carbon, reduce urban glare, deter rodents, reduce run-off into waterways, mitigate soil erosion, provide a habitat for insects and pollinators, filter out sediments and nutrients before they flow into rivers and streams, reduce fire risk, protect backyard cricketers from injury and, as demonstrated by the startlingly tidy aprons of close-cropped turf that make up our often-unused front lawns, meet a certain aesthetic standard.

The High Line, an elevated linear park in New York. Photo/Getty Images

The class of grass

Our relentless pursuit of this standard has deep roots. Mark Hostetler, a professor of wildlife ecology and conservation at the University of Florida and frequent visitor to New Zealand, suggests our obsession with these high-maintenance, low-diversity versions of the meadow and the prairie originates in the grazed savanna landscapes of Africa, where early humans could be easily alerted to prowling predators.

“As we moved from hunter and gatherer to agrarian societies,” he says on the phone from his Florida office, “we had more time on our hands and those people who could afford to control their environment had more status.”

From medieval times, manicured lawns became a sign of prosperity for those who had so much land they could put aside a portion that did not have to be used for livestock and so much money they could afford hired hands to keep them short. In 17th-century France, immaculately trimmed and bordered grass was a requirement of decorative geometrical gardens, a mannered illustration of private wealth and the power of man over nature. The English landscape of the 18th century presented a softer but no less contrived vision of urbanised nature: grazed grasslands (with grasses native to that country), a few well-placed trees for shade and a grassed “pleasure ground” of cut lawn close to the family manor.

A green wall at Longwood Gardens, Pennsylvania. Photo/Getty Images

But these were not the scalped monocrops we see today. Cut with shears, scythes or sickles, such lawns included a diverse mixture of herbaceous flowering plants, or forbs, forming a “flowery mead” of wildflowers attracting the attention of insects, birds and small mammals.

The advent of the lawnmower in 1830 put paid to the wildflowers and also brought this semi-pastoral idyll within reach of middle- and working-class homeowners – suddenly everyone could have their own small apron of shorn parkland.

Early English settlers brought this vision to New Zealand, along with their trunks and porcelain tea sets. Although hilly cities such as Wellington – now leading the country in nature restoration – and New Plymouth proved difficult terrain for this manicured ideal, flat, dry, largely deforested cites such as Christchurch were better able to keep on top of nature “so there was nothing to stop the oak trees and daffodils and lawns”, says Jon Sullivan, senior ecologist at Lincoln University. “Up here (as we sit in a cafe in the Cashmere hills) it is hilly and rugged; up here, there are fantails and bellbirds and kererū and all the things people say that they love. Down on the flat, where you can keep things very tidy and mown, Christchurch is very tidy and mown, dominated by house sparrows and blackbirds and starlings.”

A green wall at a shopping centre in Shepherd’s Bush, London. Photo/Pamela Stirling/Listener

But that tidiness comes at a cost. Although grass takes carbon from the atmosphere, once you take motor mowing, irrigation and fertilisation into account, lawns actually produce more greenhouse gases than they soak up. Mowing also produces wound-induced volatile organic compounds, known as green-leaf volatiles. These give a freshly cut lawn its seductive sign-of-summer smell, but also contributes to the formation of ozone and secondary organic aerosols, which are detrimental to human health.

Nitrogen-based fertilisers produce nitrous oxide, a greenhouse gas about 300 times more potent than carbon dioxide. Along with herbicides and pesticides, they have been found to degrade water quality, contaminate groundwater and play havoc with pollinators (a 2019 report published in Biological Conservation concluded more than 40% of insect species are declining and a third are endangered, mainly because of intensive agriculture and the use of synthetic fertilisers and pesticides including neonicotinoids, which have been linked to colony collapse in honey bees).

There is also a financial cost. On average, respondents to the University of Auckland survey spent about $277.10 a year on lawn maintenance, including lawn treatments and equipment upkeep. Overall, Aucklanders spend about $130 million a year on their lawns.

There’s also a danger factor. Last year, the Accident Compensation Corporation paid out $8.6 million for nearly 7000 lawnmower injuries and $931,485 for 1000 weed-eater claims.

A grass-roofed cabin in the Faroe Islands. Photo/Getty Images

Wild and woolly

“It is a crazy waste of resources spending time and energy trying to kill nature, especially when it is our own indigenous nature,” says Christchurch ecologist Colin Meurk. “Yes, there are some weeds you don’t want in your lawn, but the millions of dollars and carbon poured into the atmosphere to maintain these lawns and then having to constantly mow it – it is a self-defeating enterprise. Everything about that is against the sustainable future we need to be nurturing.”

About 15 years ago, Meurk began a slow siege of his own suburban lawn in south Christchurch. He planted trees and shrubs that shaded out grassy lawn borders. He planted small plugs of native plants – Leptinellas, different species of Hydrocotyle – into the lawn. Patch by small patch, the grass died out or was overtaken by native species.

“To some extent, it was a demonstration against the convention of sterile monocultural lawn with a single grass species, pouring on broadleaf herbicides and water and fertiliser, then spending all weekend arresting that growth. It is not a conventional idea of what a lawn should be – it looks a bit wild and woolly.”

At the back of Sullivan’s Cashmere garden, a quiet revolution is going on. On the shaded edges, weeds and native plants are getting a foothold in the lawn. Where the chickens have not grazed, insects hum and lizards scuttle in the long grass.

Rooftop gardens in Monte Carlo. Photo/Getty Images

“We wanted skinks in the yard and skinks need somewhere to hide from the cats so having a bit of long grass in the corner of the garden is a nice place for them to hang out. But I am an ecologist – ecologists are more tolerant of untidy.”

Across the urban landscape “untidy” is gaining traction.

In the US, UK and Europe, floral lawns, wildflower meadows, grass-free parks, urban forests and areas of “spontaneous vegetation” are proliferating in a bid for more biodiversity, more insects, more birds and less mowing. Even in winter, when such plantings look scrappy at best, there is increasing acceptance of a wild, messier urban look over short-mown grassland.

Some of this has been attributed to cost – a third of urban park managers in the UK have had budget cuts of more than 20% in the past two years; Auckland Council has stopped mowing berms. But it is also about making the most of what land is available in our cities and city edges.

Bosco Verticale (Vertical Forest), a pair of residential towers in Milan, Italy. Photo/Getty Images

In our nature

Six years ago, the Paekākāriki Orchards and Gardens community group (POG) dug up their berms and planted future trees and veges. “We didn’t have a community garden,” says spokesperson Mark Amery (they have since secured an appropriate site), “so it seemed an obvious thing to do. People were keen to see this pathetic envelope of land outside their house become far more attractive and interesting and productive.”

Over the hill in Lower Hutt, as part of the Urban Kai arm of the social enterprise Common Unity Project Aotearoa, a cluster of Housing New Zealand/ Kāinga Ora homes have turned their backyards into vege gardens, providing food for the owners and produce for the Common Unity kitchen hub’s school lunches programme.

In Canterbury, Te Ara Kākāriki has been working with landowners and schools to transform grassed corners of their paddocks or playgrounds into pockets of native plants. The resulting “green dots”, says co-ordinator Letitia Lum, are stepping stones for a greenway that will one day march across the plains from the mountains to the sea. Although funding is directed to owners of large blocks of land, more native plants in residential gardens, she says, are still valuable. “There are lots of reasons for planting native plants: as a food source for birds, for mental health, to remind us of our heritage.”

Residential gardens are also expected to feed into the new 10% target for indigenous planting in New Zealand cities, a goal recommended last year by the Biodiversity Collaborative Group. University of Waikato’s Bruce Clarkson, head of the three-year-old Government-funded People, Cities & Nature research programme, says the goal will require restoration and new plantings on mainly public land “but more native plantings in residential gardens will support these larger-scale projects. We have been raised to think a garden has to look a particular way – nice, tidy, sharp edges, managed neatly – but that possibly needs some rethinking. There are parts of the landscape where we could relax a bit and, with some judicious native planting, reduce that lawn footprint and get these additional benefits in terms of buffering and supporting the restorations we are trying to undertake.”

Native grasses in Flaxmere Garden, North Canterbury. Photo/Flaxmere Gardens/Supplied

Lawns, too, have a role in the push to get more biodiversity into our cities. By taking our foot off the lawn-management pedal, cutting back on watering (the grass may go brown but it will grow back), laying off the fertilisers and herbicides and watching the grass grow a little longer, homeowners, says Meurk, can promote the growth of more indigenous alternatives to single-species exotic grass.

“Every little niche, even in our most modified environments, is capable of supporting our nature – not someone else’s nature but our nature. So there is a role to play for even the humble lawn in biodiversity conservation and ecological literacy – getting to understand and know our species. If gardens aren’t managed to death they will often have a bit of native Oxalis or Hydrocotyle and these might seed into the edges of grass and as the density of grass lessens it will provide opportunities for those species to move in.”

With less water over summer, our lawns might look dry, “but we put up with dead, dry leaves of English deciduous trees – it is a mark of the seasons and we should rejoice in that. Having the sprinkler constantly on is just not sustainable.”

Such lawns will be less fertile (although grass clippings left on the lawn will feed nitrogen back into the soil), but poorer soil can promote more diversity. Bruce Burns, a plant ecologist at the University of Auckland, calls this the “humpback response” – in very low-fertility soil it is difficult for plants to grow; in very high-fertility soils one or two species will dominate and kick out the rest. “So, I’d be going for slightly less fertile soils that allow a range of species to co-exist. And a lower-fertility soil will grow more slowly, so you won’t have to mow it as often.”

“Minimal cut” grass beside the Heathcote River in Christchurch. Photo/Sally Blundell/Listener

Bee motivated

Just mowing grass every three to four weeks rather than every fortnightly, Burns says, will encourage more diversity and allow lawns to produce flowers that attract more pollinators and support bee populations.

“People think of lawn as an unchanging green tablecloth, but there’s enormous biodiversity associated with lawns – a whole range of flowers that attract birds and insects that live in our lawns and, underground, all the fungi and the whole biota associated with those ecosystems. So, the idea is to maintain the lawns but reduce the costs and increase the benefits.” Intensely managed short-cropped lawns are still the best option for such large areas as sports fields, “but there are edges of our parks and golf courses that could be less managed or managed for other values. We have enough grassland to try to manage different areas in different ways.”

Where lawns have been left to their own devices, the ecological changes are dramatic.

Last year, artist and environmentalist Adrienne Grant teamed up with the Hamilton City Council to mark out 13 large circles of grass across five of the city’s public parks that were not to be mown or tended in any way. Five months later, the inverted crop circles were bursting with grasses, clover, chamomile, wildflowers, bees and other insects.

“I had no idea what was going to grow there, but just letting the grass do its thing, giving the plants the ability to flourish – it was outstandingly beautiful,” says Grant.

In Auckland’s Waikumete Cemetery, cut flowers left on the graves of loved ones have spawned a small meadow of self-sown Ixia, Gladioli and other exotic species. “It is now a wildflower reserve,” says Burns. “One option is to manage some areas as wildflower meadows – mowing them less frequently and adding species to make sure there are flowers at different times of year, which could help our pollinators.”

Shortly after the Government designated a 600ha swathe of river corridor in Christchurch a residential red zone, Denise Ford, co-chair of what is now the Avon-Ōtākaro Forest Park, negotiated with officials to fence off a few areas of old gardens and excuse them from lawn duty. Although the rest of what is now called the Ōtākaro-Avon River Corridor continues to be mown and sprayed, these eight patches are harbouring small forests of ribbonwoods, kōwhai, hoheria, lemonwood, cabbage trees and a few tōtara (as well as weed species such as broom, buddleia and invasive grasses – all hand-weeded). “Once established and growing tall, they overshadow the grass and grass will die off,” says Ford. “Even in the cracks on the old roads, where contractors don’t spray, you get all sorts of things growing – cabbage trees, akeake. You don’t have to mow it to within an inch of its life.”

A flowering berm in Mt Eden, Auckland. Photo/Listener

Shabby chic

But, as Burns discovered when trying out different lawn-management processes, a nicely kept lawn is a social norm. “We still don’t understand what drives people to work on their lawns so assiduously. Perhaps it is a status thing, that people looking at a mowed lawn will have an impression of how good a person I am. It’s funny, isn’t it? I mow my berm – everyone on our street does. It’s not my land, but if it’s overgrown it somehow reflects on the homeowner.”

Successfully challenging that norm does rely on having understanding neighbours. In Florida, Hostetler has been encouraging people to stage a managed retreat of the lawn, to turn their front yards into a desert community of native plants that provide habitat for wildlife, and encourage local residents to recognise the beauty of “wild, structurally diverse native-plant yards”.

But, to keep neighbours onside, he ensures there are adequate “cues for care” – small measures that indicate a landscape is still being attended to and cared for: mown lawn borders, fences, general garden tidiness, information panels on public land. “It often takes just one maverick in the community to do something different and explain why. Even ‘messy’ landscapes will be regarded as acceptable if people truly understand the purpose.”

Even then, it may require a bit of give and take. In 2016, Christchurch City Council tried a no-mow policy on the banks of the Avon, Styx and Heathcote rivers to improve the spawning habitat for the whitebait species īnanga and the ecology generally.

Low-maintenance borders around lawn don’t require as much watering. Photo/Getty Images

“We used to scalp the riverbanks and have these bowling greens right up to the river edge,” says the council’s drainage manager, Keith Davison, “but that was actually impacting on the ecology. The scalped banks were well liked by geese and mallards over some of the native bird species and they were not good for spawning.”

Despite the project’s success – more īnanga spawning, more native scaup attracted to the relative safety of the longer vegetation – some residents complained (or simply mowed the banks in front of their properties themselves). The following year, after a particularly wet season, cumulative growth along the river’s edge blocked views of the river altogether and the complaints line ran hot. Last year, the no-cut policy was replaced by “minimal cut”, in which longer grass is left at the bank edge then feathered back to a closer cut by the roadside.

“We could see it had gone way beyond what we considered reasonable and what was necessary to achieve our ecological objectives,” says Davison. “So, we’ve been cutting the banks, not scalping them, and cutting them shortish over winter when there’s no ecological impact. It is not the bowling-green standard we had before, but it keeps the banks healthy from a spawning perspective. It looks tidy, but it is more of a natural environment without it getting overgrown and scruffy.”

These more natural, slightly messier pockets of indigenous urban landscape, says Jon Sullivan, will attract the native flora and fauna we clearly value. “Repeated surveys show city dwellers want more native plants and birds, but both of those things are kept in check by this constant tidying and the open-grass environments we feel we want to maintain.”

That, he says, can change. “Cities are always going to be altered landscapes. That is the great thing about cities – we are inventing these landscapes as we go so they don’t have to be like they have always been. If we want more native birds, we can get more woody cover and more native trees and they will come.”

Mixing it up: a green wall with a variety of plant species. Photo/Pamela Stirling/Listener

A lawn like no other

New Zealand is not awash with native sward grasses – tussocks, yes, but not the sort of grasses or even matt-forming herbaceous plants that could take the regular pounding of sports boots, hockey sticks or backyard rounders. But there are a number of low-lying plants that, once established, will cover the ground in a grass-like fashion. These include:

  • Leptinella species
  • Hydrocotyle species
  • Centella
  • Lobelia (or pratia) species
  • Coprosma species
  • Muehlenbeckia axillaris (pōhuehue)
  • Mazus species
  • Native plantains
  • Oxalis exilis
  • Dichondra species (including Mercury Bay weed)
  • Selliera radicans
  • Biddibids (barbed biddibids may not make for a pleasant lawn if allowed to go to seed)
  • New Zealand mint (Mentha cunninghamii)

Fanning the flames

Letting the lawn go, to encourage biodiversity, requires a new gardening plan.

Longer grass may attract insects, but in summer, in particular, it can fuel fires. Fire and Emergency New Zealand national adviser Pete Gallagher recommends shortening the grass early, rather than waiting until the middle of summer and running the risk of fire from sparks from the lawnmower.

“Especially as grass browns off over summer, you want to keep it a little bit shorter, particularly when close to buildings and other structures. Even if the grass looks quite green, it can be quite dry when humidity is low and wind is high. As a general rule, anything under 100mm won’t support a high-energy flame front – the fire will flash across and then go out.”

He points to last summer’s fire in Nelson’s Pigeon Valley. Raging across more than 2300ha, it was caused by a spark from a disc plough igniting the long grass.

Now, too, is the time to deal to any weeds, rather than digging out the sprayer in midsummer and leaving a volatile border of long, dead vegetation. Also, rope neighbours into keeping lawns under control while you’re away over summer. In fact, it’s a good time to rethink your whole gardening plan: “In New Zealand, we are not good at planting as a defence line against wildfire, particularly in the 10-acre blocks on the outskirts of town. Flaxes, even wildflowers, tend to hold moisture over the summer months, and with climate change we are seeing those warmer winds. Things dry out in summer much more than they used to and it seems the risk of fire is becoming something we need to think about.”

This article was first published in the November 30, 2019 issue of the New Zealand Listener.