There is around 18 million m² of artificial grass across all cultivated green space in the UK, more than six times the size of the city of London, finds a new report.

Working with Gentian, the Royal Horticultural Society (RHS) is the first to have used AI to map the UK’s growing spaces for its inaugural State of Gardening Report, published today.

Its director general Clare Matterson says the study has been two years in the making and that the RHS is hoping that the amount of artificial grass will be reduced by the time its next report is published in three years.

Whilst just 0.15% of domestic gardens is artificial grass, this still accounts for 7.5 million m². Researchers also found that 42% of domestic garden space is paved over – 55% of front gardens and 36% of back gardens – increasing the risk of flooding and pollution and reducing biodiversity and the garden’s potential to cool. The charity is urging homeowners to consider robust planting and permeable paving for front garden and driveways.

Mark Gush, head of environmental horticulture at the RHS, says there is a tendency to pave over front driveways, for instance, but permeable paving would be “the best of both worlds” and he hopes to see this move in a “positive direction”.

Nearly 960,000ha were plotted for the report, or 25.8 million gardens, 20.6 million of which were domestic front and/or back gardens. The average size was 244m2, with more than a third (35%) comprising of a lawn.

The report also highlighted the disparity of green space across the UK. Only 19% of Leeds was categorised as garden, for instance, compared to 41% of London, 27% of Cardiff and 25% of Edinburgh. More than a third (38%) of those who reported not having gardened in the last 12 months cited not having access to an indoor or outdoor space.

“Gardens are the most important touchstone to nature, fostering an active engagement in and understanding of plants and wildlife. That there isn’t equality in access to growing space in the UK reinforces the need to shore up garden provision in the 1.5million new homes promised by government this parliament,” says Matterson.

“It also demonstrates the need to ring-fence space and increase support and funding for the community growing spaces that should be considered an infrastructural basic.”

The RHS is calling on policymakers to guarantee “space to grow” in all housing and urban planning, so every household has access to a garden. “We really need to recognise that gardens and gardening is a human right and everyone needs space to grow,” says Alistair Griffiths, director of science and collections at the RHS. “Too many children from low-income families miss out.”