Where is All This Moss Coming From?

Recently I have been receiving quite a few identification/control samples of moss from homeowners' lawns. This plant is rather easy to identify because it forms a green mat on the soil surface. The mats are composed of threadlike growth that branches and clumps together into a slight mound. This plant is an excellent indicator of poor growing conditions; more specifically, an area low in fertility and very moist because of poor soil aeration and drainage. Other conditions that can encourage moss growth include: shade, soil compaction, highly acidic soil, and/or improper watering.

How do we control moss? We can treat the symptoms of this problem by applying copper sulfate at a rate of 5 ounces per 5 gallons of water applied to 1,000 square feet. This will kill the moss but it does not change the soil conditions which are the root of the problem. Thus, the best way to control moss is through cultural management practices. Avoid overwatering or frequent waterings. Core aerify the compacted areas and eliminate excessive foot traffic in these areas. Decrease the shade problem if possible by thinning dense trees or shrubs. The increase in light penetration should help dry the area and provide more sunlight which is needed for turfgrass growth. Fertilize properly and correct the pH if necessary so that it is between 6 and 7. If the moss infestation is not too severe, raise the mowing height. This will expose less open ground, put less stress on the turfgrass, and provide more leaf tissue for photosynthesis (plant growth). Unfortunately, some areas require a much more drastic change if something besides moss is to grow; such measures may include changing the soil grade or adding subsurface drainage and the selection of shade-tolerant turfgrasses. Some areas just do not receive enough sunlight for adequate turfgrass growth and, thus, should be converted to something else. This may be an ornamental bed with shade-tolerant annuals, perennials or ground covers; or something more structural like a walkway or patio. Some may wonder if moss control is worth all the work that I have discussed. If this is the case, then I would suggest accepting the presence of the moss. It is growing in the these areas because few other plants can tolerate such conditions and it is a lot better than walking in mud.

This article originally appeared in the April 1, 1992 issue, p. 44.

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