The Beauty of Moss

Moss knits rock to earth in the Japanese Garden. Photo: Bill Pusztai.

Moss is an integral part of most Japanese Gardens. It lends a feeling of antiquity and harmony to the garden; it knits rock to earth and pulls individual plants into unified compositions. As moss absorbs sound and exhales moisture, it produces a calming quality.

The Japanese word for moss is koke. It is believed that moss invited itself to gardens, and sometime around the 14th century some Zen Buddhist monks recognized the serenity it gave to the garden and they began to value its presence. A famous moss garden in Japan is Saihoji in Kyoto. The mosses planted themselves and the happy ones grew and multiplied.

Mosses are ancient plants, even older than ferns. Moss is classified as a Bryophyte, and there are over twelve thousand species. Without a vascular system, movement of nutrients occurs by cell-to-cell transfer (osmosis). Lacking true roots, mosses grow on top of the soil (not in it) and attach to substrates by rhizoids. Leaves are one cell thick. With the proper humidity moss can absorb nutrients from the air and actually cleans the air as it absorbs nitrates and ammonia. They prefer nutrient poor soil, but can thrive on acid soil, in shade, and the top of rocks with no soil. In drought conditions mosses can shrivel to conserve water and when moisture returns they return to a lush green. Mosses reproduce by windblown spores and the best way to cultivate mosses is by using the ones that are already on site.

As moss adds many varieties of textures to the garden, it shows a visual strength. But it also has a physical fragility. Moss gardens look deceptively easy to care for but in truth they require high maintenance. All errant weeds must be removed before they overtake the moss. Any fallen leaves or debris will quickly kill the moss below by shutting out the light. Sweeping must be done gently to avoid pulling the moss off the ground. Birds like to build nests with mosses and often turn over clumps of mosses to look for insects living underneath. Damage is caused by air pollution, motor exhaust, drought, too much moisture, excessive sun or shade, foot traffic

Public moss gardens in the Pacific Northwest include Seattle Japanese Garden, Portland Japanese Garden, the Japanese Garden at Bloedel Reserve, and Nitobe Garden at University of British Columbia in Vancouver, B.C.

The original article was written by members of the Arboretum Unit 86 Plant Committee: Kathy Lantz, Hiroko Aikawa, Maggie Carr, and Kathy Lantz.  Edits were made by Rumi Tsuchihashi, who is the Stewardship and Events Coordinator at Seattle Japanese Garden, and blog editor.