The Tiny Forests Popping Up Across City Blocks

Tiny Forests are sprouting on plots the size of a tennis court in cities around the world, dense thickets of native trees planted shoulder to shoulder where a parking lot or a patch of lawn used to be. In one English town this year, nearly one hundred volunteers aged three to ninety-six spent two muddy days planting more than six hundred young trees on a three-hundred-square-metre plot at the edge of a playing field, according to local reporting on the project. They left behind a pocket woodland that, if the method works as promised, will grow faster and denser than any conventionally planted grove.

The technique is called the Miyawaki method, named for the Japanese botanist who developed it in the 1970s. The recipe is simple: survey the native vegetation of the area, enrich the soil, then plant dozens of native species extremely close together — often three to five saplings per square metre — in layered tiers from canopy trees down to shrubs. Competition for light forces the young trees upward, and the claim, repeated by advocates for decades, is that the resulting forest grows far faster than standard plantations, supports far more wildlife, and cools its surroundings while it does it.

Cities are buying in at remarkable scale. The Indian state of Punjab has announced plans to develop six hundred fifty micro forests using the method, each on roughly three hundred square metres with four to five hundred saplings drawn from thirty-five to forty native and fruit-bearing species, according to the state forest department's announcement. Nairobi has been planting with the technique since 2007, with more than two hundred thirty-six thousand seedlings established at sites including university grounds and city forests. This March, Edge Hill University in England planted its own micro-forest along a campus trail with students, grounds staff, and the local council, part-funded by the university's waste management partner. Keziah Stott, the university's corporate sustainability manager, said in the announcement that "this small plot really will make a big difference to biodiversity."

What the measurements actually show

The cooling claims have some of the strongest evidence behind them. Researchers who measured soil temperatures inside eleven tiny forests in the Netherlands between 2018 and 2021 found differences of up to twenty degrees Celsius on very hot days compared with nearby asphalt, with an average annual cooling effect of about seven degrees versus streets and around ten degrees during summer. A separate study of two young tiny forests in England found consistently lower soil temperatures than adjacent control plots across a four-month growing season, suggesting the microclimate effect kicks in early.

The biodiversity numbers are striking too. Dutch researchers recorded roughly one thousand one hundred sixty-seven species of plants, fungi, and animals across the tiny forests they surveyed, including more than six hundred animal species and nearly three hundred plant species. Carbon figures are more modest and far more variable: the same Dutch survey estimated an average of about one hundred twenty-seven kilograms of carbon dioxide sequestered per tiny forest per year, but individual sites ranged from barely four kilograms to more than six hundred, depending on age, density, species mix, and plain luck. The benefits are real, researchers say, but they are uneven — and they take time to mature.

The hype has outrun the science, reviewers warn

That unevenness is exactly what worries ecologists. A 2026 review in the Journal of Applied Ecology examined fifty-one publications on the method and found only twenty-one contained quantitative assessments; just seven included a control group and three included replications, as summarized by EarthTalk. The reviewers found weak or no evidence supporting many of the headline claims about accelerated growth, carbon sequestration, biodiversity gains, and cost efficiency. "We are not against the Miyawaki method," study co-author and ecologist Ignacio Fernández told the environmental news outlet Mongabay. "But we are worried that a method that was designed for specific conditions is being applied everywhere."

Misapplication is the sharper concern. Planting dense woodland where grassland or scrubland belongs can destroy existing habitat rather than restore it, and trees that drink heavily can drain water supplies in drier regions. In India, where governments and NGOs have embraced the technique enthusiastically, local practitioners warn that speed-planting without ecological knowledge causes real damage. Mannvir Singh Khanuja, who runs a firm implementing the forests in the city of Indore, told Ground Report that a row of trees "works like a green barrier" and "can make a slight difference in temperature," adding plainly: "But it cannot create that moisture, that biodiversity."

The honest framing, scientists say, is that tiny forests are one tool in the restoration toolbox, not a universal hack. Planted with genuinely native species in places where forest is the natural ecosystem, they create valuable pockets of shade, habitat, and cool air — and they give neighborhoods, schools, and campuses a project that hundreds of volunteers can build in a weekend. The same trend is visible in new research into how plants sense their surroundings and in citizen discoveries that keep expanding botany's map. But as the fight over a single felled tree showed, what matters most is matching the planting to the place. Tiny Forests earn their keep when cities treat them as the start of an ecology, not the end of one.