Everyone in this part of the country is familiar with moss. Love it or hate it, it clings to roofs, rocks, tree trunks and soils in shady places in our humid New England climate.
Conditions favorable for growing moss are: shade, an acid (low pH) soil, low fertility, and wet, compacted soil. Those who try to cultivate a lawn when all of these conditions are present face a sisyphean task, since turf grasses prefer bright light, a pH of about 6.5, good fertility and drainage. Although Rough Bluegrass (Poa trivalis) is somewhat tolerant of wet, shady sites, moss is likely to win out where it’s better adapted.
Mosses belong to a family of 12,000 species in the plant division Bryophyta. Low growing due to their lack of a vascular system, they form colonies in damp, shady conditions. Although they are found clinging to trees, they are not parasitic; their roots function merely to anchor them in place while water and nutrients are absorbed directly through the leaves. Like higher plants, mosses produce food through the process of photosynthesis.
Moss has commercial value, notably in the florist and nursery trades. Sphagnum is the major component of of peat, which is collected for horticultural use and as a fuel. Peat is burned to smoke malt, giving Scotch whisky its distinctive aroma and flavor. Sphagnum moss (S. cristatum and S. subnitens) is harvested alive and dried for commercial use. Peat moss can be managed sustainably by allowing regrowth, unlike moss peat which is mined with no possibility of recovery.
For gardeners who belong to the moss-as-weed camp, eradication by mechanical or chemical means is relatively easy. Physical removal with an iron rake is simple and effective. An application of one of the moss control products which contain potassium salts of fatty acids or iron sulfate found in commercially available moss control products will solve the problem in the short term. Simply killing moss and then failing to correct the conditions that favored its growth will only mean its return. Another option is to keep the moss in place of turf, or choose another shade-tolerant groundcover.
Although moss is often considered a weed in grass lawns, in some cases, such as Japanese-style gardens, it is deliberately encouraged to grow, where it said to lend an air of tranquility to the scene. Moss is a common addition at the base of bonsai.
In the Pacific Northwest, moss is frequently used as a lawn substitute for shady areas. Boulders or logs with a robust growth of moss are sought after as naturalistic garden ornaments.
If you would like to grow moss, between stones in a pathway for example, be sure that you have favorable conditions for its success. Encourage the growth of moss by making a slurry of two parts moss, two parts water, and one part buttermilk in a blender. Spread the slurry over the area and mist regularly until growth is established.
Depending on one’s perspective, moss either imparts a mellow patina of age to features in the landscape or it’s an ugly nuisance. To achieve the most pleasing results in your landscape, sometimes all that’s required is a change of perspective.