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How to prevent moss and algae from popping up in turf
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As soil becomes less fertile and more compacted over time, healthy turf thins out and its growth declines.

As with anything in nature, something will occupy a site and recently that something is moss and algae.

Moss is a branched, threadlike green plant. It forms a tangled, thick mat over the soil.

Algae are threadlike green plants that form a dense, green scum over the soil surface.

Neither moss nor algae are thought to be parasitic and both are spread by wind-blown spores. Both can form crusts on the soil surface, reducing air and water movement into the soil.

Factors favoring their development include wet and humid conditions and compacted soils with thin turf. Moss is more common in shady areas with infertile, acidic, soils and excessive thatch, while algae are in full sun conditions and fertile soils.

Cultural practices favoring growth of turf grasses will reduce the competition from moss and algae. These practices include:

Maintain soil fertility, pH

Have the soil tested to determine proper lime and fertilizer needs. For most turf grasses, the pH should be about 6.0.

Improve drainage

Soils which stay moist because of poor drainage should be contoured, allowing water to drain. In some cases, tile drainage may be necessary to correct conditions.

Increase light, circulation

Pruning tree limbs below 10 feet and selected limbs in the crown will improve light penetration and air movement. Remove some of the least desirable trees and thin and/or remove shrubs to help.

Areas surrounded by buildings and vegetation with limbs close to the ground may require considerable work to provide adequate air circulation and light penetration.

Use shade tolerant grass

If direct sunlight does not reach the ground during the day, an ornamental ground cover may be better suited to the site than a turfgrass like tall fescue.


Generally turf may be renovated if less than 50 percent of the area has the desired turf. Chemical control can be used to kill moss and algae if you are planning on renovating. Use products labeled for moss and algae control. But complete as many of the previous cultural control suggestions so growing conditions are changed to favor turf growth and not moss or algae growth.

Cultivate compacted soils

Aerification with a machine that removes plugs of soil will help reduce compaction. Core aerifiers may be rented from various equipment rental companies, or contracted though a lawn service company. Drainage in fine textured soils can be improved by cultivation and adding large amounts of organic matter.

Irrigate deeply, infrequently

Avoid light, frequent irritation. Wait for signs of moisture stress in your turf such as the development of a bluish-gray, dull color before irrigating. Then irrigate to wet the soil at least 6 inches. Most healthy turf grasses need about one inch of water per week during active growth.

Michael Wheeler is county extension coordinator for the UGA Cooperative Extension office in Hall County. You can contact him at 770-535-8293, His column appears weekly and on


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