One of the more frequent questions lately has been, “What can I do about the moss that is taking over my lawn? There are several reasons for moss in turf. The moss is the symptom not the problem. Moss takes advantage of the situation where there is no longer any grass in shaded or moist soils. Moss favors damp areas where air circulation is limited. Problem areas may also be compacted, poorly drained, infertile or have an incorrect pH.
Moss most often occurs in areas under trees where the turf doesn’t receive good sunlight and airflow. You may say, “but I have moss growing in an area where there aren’t any trees.” Our soils often have a higher clay content, which can easily become compacted creating a poorly drained soil. A compacted soil in full sun can easily support moss growth.
One of the most important factors is to try to manage your grass correctly with regard to mowing height, fertility, and pH. A soil test every three to four years will ensure the fertility and pH stay in the correct range. Fine fescue should be mowed at a height of 2 to 2 ½ inches compared to 3 to 3 ½ inches for tall fescue.
A fine fescue instead of tall fescue will be required in shady or limited light situations. Tall fescue will gradually die out in shade. Examples of fine fescue are creeping red fescue, chewings fescue, and hard fescue. When renovating a lawn, it is best to overlap seeding of fine and tall fescue and allow the specific environmental conditions dictate which type of grass will perform best.
Improving the penetration of sunlight and airflow into an area will drastically improve the survivability of a turf in shady areas. This can be accomplished by pruning or removing trees. Removing limbs below 10 feet will probably allow adequate light in many situations.
Over time, the soil may become compacted, reducing the surface and internal drainage. The result will be a soil that tends to stay damp, causing the soil surface to stay wet. This is a great place for moss to become established in the absence of grass. This compaction may be relieved by core aerifying a soil. A core aerifier will actually pull a core of soil and leave it on top of the ground and these cores can be left on the ground where they will gradually break up.
You can chemically remove moss by applying copper sulfate, iron sulfate, ferrous sulfate, sulfate of ammonia, and hydrated lime. Without addressing the issues discussed in this article, the removal of moss will only be temporary.