Cultivating Moss in Gardens
I love moss. A carpet of moss is soft and vibrant, but also conveys a sense of age. It takes new boulders and rubs the sharp edges down, makes them seem a bit alive.
But how do you cultivate moss? Can you plant it? Encourage it? Nurture it?
The article below, one of the best I have ever read on the cultivation of moss in Japanese gardens, is by Dale Sievert. Dale is an avid gardener and garden writer. This article was originally published in the NAJGA email newsletter. He also writes for Sukiya Living Magazine (The Journal of Japanese Gardening). Looking for more on moss cultivation? Check out his blog.
Moss Cultivation A World Apart by Dale Sievert for NAJGA
I often visit Japanese gardens during my extensive travels. In Japan, I’ve visited about 60 gardens. In North America, I’ve been to about 25, including most of the top-ranked gardens. The biggest difference I’ve seen in the two groups is the cultivation of moss. In Japan, all of the gardens cultivated mosses. In North America, less than 10 did.
Moss, especially when hydrated, can be instrumental in creating the tranquility, serenity, and beauty for which Japanese gardens are known. I believe that almost all North American gardens are missing a great opportunity to enhance their gardens. Only Nitobe Memorial Garden at the University of British Columbia in Vancouver and Portland Japanese Garden in Oregon have what I judged to be adequate use of moss.
Some would say that mosses don’t do well where their gardens are, so they don’t even try. But I always find at least several species of moss in or nearby almost every garden I visit. Even hot, dry areas, such as the southwest of the United States have mosses, though they are more scarce than more humid areas.
So, if you are the director or curator of a Japanese garden and want to introduce mosses, what are the most important things to know or to do?
Above all, locate as many species growing locally as you can. Always get permission from the property owner before doing any searching. Then hydrate them if you find them dormant, as mosses can change color and appearance dramatically when going from dormancy to the hydrated state. Then select three or so for a test in your garden. It is of utmost importance to match the environmental conditions of the garden to the harvesting site as much as possible. Light levels, especially hours of direct sunlight, if any, is the most important criterion. Probably second most important is soil moisture level. Some mosses prefer wet conditions, others dry with only occasional wet times. Next, match substrate conditions, whether silt loam, clay, sand, or bog—or hard substrates such as trees, rocks, etc. This is not always critical, but enough to assume it is.
With most species of moss, harvesting is best done with a (rectangular) garden spade. Try to collect a half inch to an inch of the substrate on which the moss is growing. Almost all mosses are attached to the substrate with tiny extensions of the stem called rhizoids. These only serve to hold the moss in place so wind doesn’t move it. Mosses have no roots for the uptake of water and nutrients, as they get that through their leaves directly from the air. A few mosses are three or so inches thick and often appear to lie unattached on the substrate untethered. These can simply be lifted up off the substrate. Try to collect sections about one square foot in area.
In the garden, lay the collected sods on the substrate which has been prepared ahead of time. Fit the sods as tightly together as possible. After the entire area is covered, water the moss thoroughly, enough so the substrate is wet, as well. Next, push down on the moss, either by hand or by lightly stepping on the moss. The intent is to remove air space between the substrate and the moss sods. That helps to foster growth of new rhizoids, which takes weeks to several months, depending upon the species. For the first week or two, lightly water the moss once a day, then only sparingly thereafter, unless a severe dry spell occurs. Depending upon the species, in a year, sometimes two or three, the sods will become a single mass as the mosses grow, usually horizontally.
This process of collection and establishment is the same, whatever the geographical area. However, the actual species that will be the most successful varies a great deal with geography. I’ve found a few mosses growing throughout the country, as well as in Japan, Europe, and Africa. Most, however, are limited to smaller areas, due to differing levels of humidity, rainfall, sunlight intensity and angle of incidence, and soil type and pH levels.
Polytrichum commune is the most common moss species I’ve seen in Japanese gardens, and it covers about 80 percent of gardens in Japan. It is also widely prevalent in gardens of the Pacific Northwest. But it can also be found in gardens of the East—though less commonly. It is one of the most commonly commercially available moss, commonly called Haircap moss. However, I have only seen it doing well on acidic soils, and I never see it in natural settings with alkaline soils. Another moss I’ve seen in Japan, New Zealand, throughout North America, and in Armenia is Hedwigia ciliata. It is unusual in that it does well in both shade and full sun, and it is almost always found on rocks and concrete. It is harder to move, however, as it has to be scraped off hard surfaces and attached to new homes with a bit of 100% silicone caulk. Thuidium delacatulum is one more moss I see in many parts of the world, so long as it gets plenty of water. It grows in thick mats and can be strikingly beautiful when hydrated.
Other widespread genera of shade-loving mosses include Plagiomnium and Brychythecium, with several species each. Widespread sun-loving genera include (I’ve seen them everywhere) Bryum and Ceratodon. Thus, they should be the choice of gardeners in the Southwest. Another good genus there would be Syntrichia.
For gardens east of the Mississippi, other genera include, Entodon, Atrichum, Bryoandersonia, Fissedens, Climacium, Anomodon, and Rhodobryum.
The finest moss garden I’ve visited in North America is Nitobe Memorial Garden in Vancouver, British Columbia. Large expanses of its moss lawns include the species Pseudotaxiphyllum elegans, Rhizomnium glabrescens, Plagiothecium undulatum, Plagiomnium insigne, Eurhynchium praelongum, and Hytidiadelphus squarrosus. I’ve never seen any of these where I live in Wisconsin. My guess is that they would grow well along the Pacific coast from British Columbia down to the California border.
The joy I receive when I walk through the moss gardens in Japan, some in North America, and my own extensive moss gardens makes me feel sorry for those who never get to have that experience. That does not have to be.
Commercial sources of moss:
Mountain Moss Enterprises
www.mountainmoss.com
Brevard, North Carolina
1-828-577-1321
Moss Acres
www.MossAcres.com
59 Bates Road
Honesdale, PA
1-866-GET-MOSS