Berks County Cooperative Extension -

MOSS GARDENING

How and Why to Encourage Moss (Phylum - Bryophyta) in Some Areas of the Landscape.

Introduction.

Many types of moss can provide a beautiful green carpet on our soil year round. Moss does not require mowing, fertilizing or good soil like grass does, and in most areas, when established, requires much less water than grass. While grass can be particularly difficult to grow in shady locations, especially if shallow rooted trees or shrubs are competing for moisture, many mosses prefer shade. Since mosses do not have true roots, they can often absorb sufficient moisture from the air, or from a two-minute sprinkle. Some moss will turn brown during a severe drought, reviving when moisture returns. Some species are known to survive for as long as ten years without water. Many mosses are more durable and more attractive than many think and the carpet forming varieties overwhelm most weed seedlings so that the need for weeding is minimal. Most diseases and insects that affect grass do not bother moss, although moss does not like air pollution (it is seldom found along the roadside) or drought. Moss is also adversely affected by some birds, rodents, weeds, excessive sun or shade, or poor drainage that leads to damping off. Microscopic moss spores are common in the air, so it does not have to be expensive to encourage moss areas in the landscape.

Gardeners will find areas of moss already present on their lots that will only need encouragement instead of the discouragement that some fertilizer proponents recommend. Some of the moss enthusiasts discussed below feel it is easier to maintain (it does not require dethatching or aeration) and is more environmentally friendly than most grass, since lawn mowers are noisy and polluting, and fertilizers often run-off or get into the water table and pollute our water supplies. In addition, Lindsay Totten (Reading Eagle, 1 January 2001, p. C3) states, "Turf grass pollutes the air. Lawns release significant amounts of volatile organic compounds (butanone, ethanol, methanol and propanone), adding to smog problems. Emissions increase by 180 times when grass is cut…"

Growing generally.

Many mosses grow easily on compact clay soil and most types can be easily encouraged by an acid soil (pH 5.5 is optimum for many types) and by moisture. Some types spread fairly quickly (6-12 months) on their own, if soil conditions are optimum and many types do better in the shade than in the sun. All types do better if adequate moisture is available. Established moss can normally survive with only rainwater and moisture in the air. The main growing season for most mosses is the transitional chilly, rainy, and damp weeks of late autumn and early spring.

Skim milk powder and fertilizer.

George Schenk's book, Moss Gardening , describes many different varieties of moss with many excellent photographs of moss-covered landscapes. Some moss is very particular, in some instances preferring shade year round such as beneath a conifer tree, other types preferring just the type of shade offered by a hardwood tree, while still others are not as fussy. He describes five different ways to establish a moss lawn and mentions the use of skim milk powder or rhododendron fertilizer as alternatives to the acidifiers discussed below. Schenk describes the use of products such as Roundup® to clear an area of grasses and weeds in order to allow nature to establish a moss covered area, but this method can take several years to achieve complete coverage by moss. If one has an area where moss and grass are coexisting, the grass can be pulled out to allow the moss to spread to form a carpet.

Transplanting moss.

Schenk describes numerous types of moss that prefer different types of soil conditions. He describes methods for the immediate establishment of mossy areas by transplanting moss from nearby properties (to a similar location, especially as to amount of sun/shade). If permission cannot be obtained to transplant already growing moss, it can be purchased from various sources listed under 'Additional Resources'. Transplants should be the size of an outstretched hand. Schenk recommends using a spade or a butcher knife with a long stiff blade to dig moss. There is no preferred season for transplant of most moss, unless it will be neglected, and then the rainy season would be best.

Planting moss sods.

Another method used to establish moss is to plant moss sods at spaced intervals, allowing them to grow together. Schenk states that this method "can be used in the installation of carpeting moss of any kind and is the usual method of planting that foremost of mosses for sunny sites, Polytrichum." A slow growing dark green variety such as Polytrichum will likely require two or three years to provide a nice contiguous carpet of moss. If moss sods are not watered adequately during the first year, they may shrivel and turn brown and stop growing but they will soften and green when adequate moisture returns, if they have not reached the point of fatal desiccation. Although moss in the wilderness can withstand long-term drought, transplanted moss can be killed quickly if allowed to dry too much, or placed on the wrong soil or in the wrong sun environment. Polytrichum differs from many mosses in being a deep-rooted variety so it is best planted with a 2- to 3-inch depth of the native earth. Many moss varieties only need the thin layer (less than 1/4 inch) of soil that clings to the plants roots (rhizoids technically) to survive a transplant. A fast growing variety of moss such as Brachythecium, if planted at the normally recommended 12 inch intervals, should unite and provide a nice carpet in as little as one year.

Breaking and scattering moss.

A few types of moss propagate themselves by breaking up and scattering themselves about. This method of growing a moss carpet is often touted in magazine articles about moss gardening. This technique is rarely used since a very limited number of the species adaptable to the technique are carpet-forming varieties. Methods of controlling spore movement during heavy rains with cheesecloth or something similar may be required on sloping terrain with this technique.

Removing debris.

Heavy seed fall from trees such as maples and ash may require hand-cleanup, according to Schenk, but it would seem like a leaf blower or vacuum might be speedier, although much noisier. He does recommend the leaf blower for small conifer needles such as those of Hemlock, stating that any layer of debris left too long will eventually smoother the moss. Since most raking of leaves from a moss carpet will cause some damage, Schenk recommends that gardeners in cold climates wait until the moss is frozen to rake the leaves, feeling that the frozen moss is more difficult to damage by raking than the softer moss. The netting that is described below is another alternative.

Local moss landscape.

A Penn State horticulture graduate, Dr. David Benner, has established a beautiful landscape at his home in Doylestown with no grass, but lots of ground covers and flowers, and moss walkways. A vicarious tour of his beautiful yard is available via video, Made In the Shade which is available for loan at the Berks County Extension office. Dr. Benner gives tours to hundreds of people each year, in the spring, explaining the ease of maintenance a moss and ground cover landscape offers. The hundreds of people walking on his moss show that at least on his lot, his variety of moss seems to be holding up very well.

He shows and explains how to establish a moss lawn by acidifying barren soil anytime of the year with aluminum sulfate or ferrous sulfate, the desired acidification being achieved in 2-3 weeks. Alternatively, sulfur dust or chips can be applied after May, but two to three months will be required for acidification to occur. Dr. Benner places a fine mesh netting over the moss areas as the leaves begin to fall. He leaves the netting in place for several months and collects the leaves by rolling up the netting.

Moss as an alternative.

No claims are made that moss holds up as well as durable grasses if football is regularly played on a lawn, but an occasional divot can be easily repaired or replaced. A moss lawn that has received rough treatment from children during the summer will heal during the winter. It is an alternative that more people may wish to consider, especially if low maintenance over the long term is a desirable objective, along with less pollution.

Just as our ideas of which plants are really weeds are changing; so, too, should we evaluate our past notions of "weed mosses." These simple plants are easy to grow, and often may be more appropriate than other choices in numerous applications.

Additional resources.

Sites that provide information, pictures and moss supplies, etc. include:

Author: Master Gardener Dennis Fink
Document created: 3 March 2001; Revised: 15 March 2001