Moss Management

Source(s): Randy Drinkard

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You may have noticed when cutting your grass recently that what was once your nice, thick, green lawn has turned into a not-so-nice, thick, green something else? What is this “stuff” that is taking over the lawn? And can it be stopped from spreading over your entire yard? Most likely the problem is moss, although in some cases it may be algae.

Moss and algae replace turfgrass when growing conditions for turfgrass are poor and conditions for moss and algae are favorable. Neither moss nor algae are parasitic on turf and they do not kill turf as diseases do.

Moss and algae are simply plants looking for a home and if the right conditions are provided, they can quickly take up residence and do well. This is the way nature intended it, so let’s see what created the conditions for these two turf pests to occur in the first place.

Mosses are small plants which produce a mass of fine stems that can survive under very shady conditions. Moss will take over and grow where the shade is so dense during the summer that not enough light is present to support growth of a turfgrass such as fescue. Moss also thrives during periods of high humidity and in water-logged soils like we had earlier this year due to heavy summer rainfall amounts.

Algae is a very simple plant that has no vascular system. It usually forms a dense green mat or scum over the soil surface, although reddish or brownish forms may also occur in some situations. Algae needs plenty of water and lots of sunshine for growth. When the soil dries, algae forms a black crust which becomes hard and relatively water-resistant.

The best solution for either of these problems is the use of a soil aerator that removes plugs of soil from the ground, thus enhancing soil drainage. However, if the affected area has very little grass, it is better to start over. Till the soil to a depth of 6 inches to break up the restrictive layer. Tilling will also facilitate incorporation of lime and fertilizer into the soil. A soil test should be taken to determine plant nutrient needs. Soils with low fertility and low pH (acidic) lead to poor growing conditions for grass and make it easier for algae and moss to become established.

Improving the drainage with the incorporation of organic matter is also beneficial. Low areas that do not drain well should be contoured. In some cases, the use of drain tiles can help remove excess water and improve growing conditions for turfgrasses. Sometimes we may create water problems by watering too much. Irrigation systems should be adjusted to match the soil conditions and plant needs.

Moss can become very thick under heavy shade conditions. Thinning trees or pruning limbs to improve light conditions and increase air circulation is often helpful. If grass won’t grow in these areas it may be necessary to utilize a shade-tolerant ground cover or simply cover the area in mulch.

Some chemicals are available to eliminate moss. Their effect is only temporary and the problem will likely return if conditions do not favor turfgrass growth. Iron sulfate can be applied at the rate according label directions. This product can be purchased at local garden centers and nurseries, farm supply dealers or building supply stores. The only sure method of eliminating moss is to remove it by hand raking.

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Center Publication Number: 118