How a Classic English Garden Went Wild

By definition, gardens are thought of as green. In reality, though, the resources used to keep them looking pristine, in terms of water, fertilizers and fuel for the mower, are staggering. How can we garden in a way that’s better for biodiversity and sustainability?

The Walled Garden at the Knepp Estate in West Sussex, England, is posing this question dramatically. The 1.3-acre plot sits within Knepp’s 3,500-acre expanse, the site of one of the first large-scale “rewilding” projects in England. Since 2001, Knepp’s farmland, once a high-intensity, high-input mixed arable and dairy farm, has slowly returned to a system of natural processes, a journey that Knepp co-owner Isabella Tree documented in her 2018 book, Wilding: The Return of Nature to a British Farm.

Knepp’s head gardener, Charlie Harpur, describes rewilding as the restoration of key interactions between animals, plants and the environment. “Without these interactions—browsing, grazing, rootling, trampling, flooding, frost, et cetera—we don’t get that mosaic of different habitats that offers such a diverse range of opportunities for wildlife,” he says.

Tree says that she and her husband, Charlie Burrell, came to realize a few years back that they were treating their garden very conventionally as compared with the estate’s wider landscape. “We still mowed our lawn almost weekly through the summer,” she recalls. Meanwhile, they were hearing from a growing number of visitors who had returned from Knepp inspired to join the rewilding movement. “They didn’t have hundreds of acres. They said, Is it possible to rewild a back garden, a churchyard, a window box? So that’s how we started thinking about how you could apply the lessons…from the larger rewilding project to smaller spaces. It’s all about thinking like a beaver or a wild boar or a water buffalo.”

The garden’s transformation, begun in 2019, has been a collaboration between the Knepp team; garden designer Tom Stuart-Smith’s studio, where Harpur formerly worked; and a group of horticultural advisers. The first step was changing the topography of the land, digging out hollows and creating mounds with the collected soil, similar to what occurs on land where large herbivores, like wild boar or bison, constantly shift the dirt. The hollows in the garden flood in wet periods, and the mounds create sunny banks, each enriching the garden’s potential for biodiversity. Next, the team had to “decide on the very complex planting palette that we thought might suit those conditions,” says Stuart-Smith. “There are nearly 1,000 taxa in the garden.”

Soil diversification was in part achieved by adding in building material from demolished farm structures nearby. “It was a bit scary dumping 400 tons of crushed brick and concrete onto the monocultural billiard-table desert of our croquet lawn,” says Tree. 

This material, when mixed with sharp sand, has reduced soil fertility in certain parts, a somewhat counterintuitive change that allows the soil to support species that are normally outcompeted on more fertile ground. Harpur has observed the arrival of some “self-sowers” from a chalk downland habitat about 12 miles away, including wildflowers like fumitory and horseshoe vetch. 

The land is still being gardened, just differently. For Harpur it comes down to mindset. Weeding is called “grazing,” channeling the eating patterns of local animals. Some plants normally categorized as weeds are left untouched to play their part. For example, Harpur notes that mayweed can protect seedlings and cool the ground temperature. “As the keystone species in this context, we can decide if something is good for biodiversity and leave it,” says Harpur. Watering is done sparingly, generally only to give plugs and seedlings a healthy start. “The idea is that the garden ecosystem we’ve created will govern itself,” Harpur says.

At Knepp, ecologists regularly log the presence of wildlife, like insects and birds, which, Harpur says, helps the team understand the impact of their management on the garden. For the average gardener, this kind of survey may seem impractical, but Knepp runs workshops and even rewilding “safaris” for home enthusiasts. “What’s known as ‘citizen science,’ or using recording or identifying apps, is important for helping us as a nation to understand the life we have in our gardens, spaces that are often disregarded as having enormous potential for wildlife,” he says. “There are 4,500 square kilometers of gardens in the U.K., which is more than the area designated to national nature reserves.”

“We’re learning to love a different aesthetic,” says Tree, who with Burrell has also written The Book of Wilding: A Practical Guide to Rewilding Big and Small, out in the U.S. later this year. “The dead seed heads left for the birds look dazzlingly beautiful in the first frosts of winter. The ‘dirty’ paths, once hoed and flame-blasted to get rid of the weeds, are now tangles of creeping thyme, chamomile and herbs that you crush with your feet as you walk. Our rewilded lawn, shaggy and full of flowers throughout the summer, now has orchids popping up in it. We look back on what we were doing with the garden in the past and wonder, How could we ever have been so stupid?”