Japan’s Emerald Carpets: The Cultural Importance and Environmental Promise of Moss

It is easy to overlook moss—small, inconspicuous, and flowerless. But Japanese have long admired this moisture-loving plant for its subtle beauty, seeing in it the embodiment of the much touted aesthetics of wabi and sabi—transience and imperfection. Moss is found in abundance in the wild and in carefully manicured gardens, and is even mentioned in the national anthem, “Kimigayo.”

Japan’s admiration of moss remains strong even today. Going for a neighborhood stroll, it is not unusual to see moss shaped into spheres called kokedama in gardens or as part of carefully-groomed terrariums brightening home interiors. People looking for a more intimate moss experience can join dedicated tours of pristine, moss-covered precincts advertised in travel magazines, or simply make dinner reservations at a Japanese restaurant overlooking a traditional garden. Japan’s obsession with moss has even produced a nascent tribe of diehard female fans who call themselves “moss girls.” Below I look at how moss came to have such lofty status in Japanese culture.

A moss display incorporating rock and wildflowers.

Animal figures add a humorous touch to a moss terrarium.

The primeval, moss-covered forest on the island of Yakushima in Kagoshima Prefecture is a popular destination for trekkers.

Gardens of the Soul

Abundance is a central factor in the centuries-old Japanese passion for moss. Fed by moisture from the East Asian monsoon, Japan’s rain-soaked climate provides an ideal environment for the country’s over 1,700 varieties of moss to flourish. Surrounded by such profusion, Japanese writers over the ages have looked to the plant to express aspects of the human condition, coining such phrases as kokemusu (to become moss-covered) to convey the slow passage of time and the idiomatic koke no koromo (moss garments) to describe the rough, unadorned robes of a Buddhist priest. Japan’s warrior class found a powerful metaphor for the transience of life in the short-lived blossoms of the cherry tree, but moss also provided a somber reminder of the unavoidable fate of all living things, as expressed in the saying koke no shita (beneath the moss), indicating that a person has gone to his grave.

Moss and cherry blossoms have deep cultural meaning in Japan.

Japanese aristocrats of the Heian period (794–1185) found beauty in moss, but preferred cherry and plum trees for their brightly colored blossoms and the Japanese maple for its brilliant autumn foliage. With the proliferation of Zen culture during feudal times, however, the plant’s rugged, simple allure came to express the values of wabi and sabi that form the core of traditions like the Japanese tea ceremony. Moss, with its soothing, earthy loveliness, became an essential element of Japanese gardens, and is still revered as something elegant and lovely today.

Moss features prominently in the garden at Zen temple Eigenji in Shiga Prefecture.

A carpet of moss covers the ground of the garden at the Nakano House Art Museum in Niigata Prefecture.

The roots of Japanese-style gardens extend back to the Asuka period (593–710), but moss did not emerge as a design element until the Muromachi period (1333–1568). Over the subsequent centuries, though, garden designers used it to full effect, producing stunningly landscaped creations such as the moss-covered confines of Saihōji, Kyoto’s famed “moss temple.”

Moss seems to cover every inch of ground of the Japanese garden at Saihōji in Kyoto. The temple is part of a UNESCO World Heritage Site.

Moss came to be used in different ways as the Zen aesthetic matured and new styles of Japanese gardens developed. A garden might have a carpet-like moss covering such as at Saihōji, small patches selectively placed to represent natural features like an island floating on the water, or mats formed into bold geometric shapes.

A carpet of moss covers the ground at the temple Sanzen’in in Kyoto.

Moss represents islands and rocks mountains in this Japanese garden at Ryōtanji in Shiga Prefecture.

Squares of moss and stone create a striking check design called the Ichimatsu pattern at Kyoto’s Tōfukuji.

Defending Moss Diversity

Design elements like shukukei, miniature representations of natural features such as craggy mountains or islets in the rippling sea, are beautiful while also providing moss a variety of environments where it can thrive. Scholarly research has shown that Japanese gardens can contain over 100 types of moss, including rare species, making them important repositories of endangered varieties. However, as urbanization changes the landscape, it is becoming increasingly necessary to preserve areas where moss can flourish.

The diverse landscape of the garden at the Hakone Museum of Art in Kanagawa Prefecture supports a wide variety of moss species.

Experts are concerned about the impact of human activity on moss. One emerging threat is rising nighttime temperatures from so-called urban heat islands. Large swaths of cities are covered in materials like concrete and asphalt that absorb and hold heat, making the environment warmer than surrounding areas and producing sweltering conditions that are detrimental to the health of moss.

A close-up of the glistening leaves of the native Japanese moss species Ezosuka-goke. Mosses absorb moisture and nutrients directly from the air and are sensitive to changes in the environment.

Moss differs from other plants such as trees and grass in that it absorbs moisture and nutrients directly through its surface cells. Morning dew and fog are important sources of sustenance, but the heat island effect prevents water droplets from forming. Meteorological records from Kyoto show that during the 1960s dew occurred 30 times each year on average, but that during the 2000s the frequency shrank to nearly zero. Subsequently, moss in areas most affected by the heat island phenomenon decreased noticeably. If left unchecked, the drastic die-off of moss will pose a serious threat to the beauty and cultural heritage of Japanese gardens.

Dead moss in a Japanese garden caused by the heat island effect.

Moss has more than just cultural significance. The plant’s sensitivity to environmental conditions also make it a reliable indicator of climate change, and scientists are increasingly looking to it to get a broader picture of the problem. However, moss populations are not only declining in cities; in wild areas, too, moss colonies are suffering serious damage as forest ecologies are ravaged by booming deer populations.

Scattered dead tree trunks along the slopes of Mount Ōdaigahara in Nara Prefecture are all that remain of a once lush, moss-covered forest. Over the last 30 years, herds of hungry deer have decimated the environment.

Moss has the potential to deepen our understanding of climate change. Scientists are already using it to study pollution levels, both locally and on a global scale. What moss tells us about the environment today will have serious repercussion for larger organisms, including humans, down the road. However, it remains to be seen if humans will listen to these tiny prognosticators before it is too late to change course to avoid a catastrophic environmental disaster.

(Originally published in Japanese. Banner photo: The moss garden at the temple Rurikōin in Kyoto. All photos © Ōishi Yoshitaka.)