Ag Line: Managing Moss Effectively
Wade Parker County Extension Coordinator

Moss does not only grow in the woods or in fish ponds. When we hear the word "moss," the first thing we think of is that slimy stuff that grows on the top of the water in ponds. However, moss can actually grow in homeowners' yards and be a problem to contend with.

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 waterlogged soils like we had earlier this year due to summer rainfall.Algae are very simple plants that have no vascular system. They usually form a dense green mat or scum over the soil surface, although reddish or brownish forms may also occur in some situations. Algae need plenty of water and lots of sunshine for growth. When the soil dries, algae form 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 breakup 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 to 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.Getting rid of moss and algae is the easy part. Improving the growing conditions for turfgrass is the key to controlling them. The University of Georgia Cooperative Extension offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.