Winter turf decline is a recurring problem in warm‑season lawns across Louisiana, particularly during wet, cool winters. This type of injury is commonly observed in centipedegrass and St. Augustinegrass, two species that spread by stolons and tend to have relatively shallow root systems. Although symptoms can differ slightly between species, the underlying cause is often the same: prolonged soil saturation combined with reduced plant transpiration and metabolism during winter dormancy.

Why winter decline develops

Winter decline of warm-season lawns is most often observed in wet or poorly drained soils. Low-lying areas or soils that contain elevated fractions of silt and clay readily retain moisture during Louisiana winters when rainfall can be frequent and evaporation is low. This moisture retention allows for soils to remain saturated with water for extended periods. When soil pores fill with water, oxygen is displaced, creating low‑oxygen or anaerobic conditions. Roots, even during winter dormancy, still require oxygen for respiration; saturated soils limit this basic function and weaken the root system’s ability to survive cold stress.

Anaerobic conditions also encourage microorganisms that thrive without oxygen. These organisms readily decompose soft or weakened plant tissues such as stolon bases and crowns, causing them to darken, soften and separate when pulled. This type of soft rot is commonly noted during extended periods of leaf and crown wetness in cool weather. Because stolons of centipedegrass and St. Augustinegrass often sit within or just above the thatch layer, they are especially vulnerable when that layer remains wet for long periods.

It is important to distinguish the difference between the harmful anaerobic decay that occurs in saturated soils and the beneficial aerobic decomposition required to break down thatch. Anaerobic decay occurs when oxygen is limited; it is fast, destructive and targets living or recently living tissue. This is the type of decay responsible for crown and stolon rot during wet winters. Aerobic decomposition, on the other hand, occurs when oxygen is available. It is carried out by fungi and actinomycetes that specialize in breaking down lignin‑rich material such as old stems, roots and stolons, all of which are components of a thatch layer. These beneficial decomposers cannot function in saturated soils, which means thatch persists and sometimes grows worse under wet conditions, even as the living turf above it declines.

As turfgrasses enter winter dormancy, shoot growth slows dramatically and root activity declines, reducing the plant’s ability to repair damage caused by saturated soils. When decay occurs during dormancy, the turf cannot reanchor or regrow until warmer temperatures return. Areas affected in winter will often show poor or uneven green‑up in spring (Image 1). In severe cases, stolons lift easily from the soil with few or no surviving roots attached, a symptom also seen in other moisture‑related decline problems.

Image 1. Centipedegrass may fail to green up in the spring due to winter decline. Photo by Judd Lobb

Several site factors increase the likelihood of winter decline. Poor draining, low‑lying and heavier silty clay soils are the most significant contributors because they allow water to pool for long periods (Image 2). Compacted soils and heavy clay textures, both common in parts of Louisiana, slow infiltration and keep roots in saturated conditions for longer. In contrast, soils with a greater proportion of sand allow water to drain more freely, reducing the risk of prolonged soil saturation. Thick thatch layers also increase risk by keeping stolons suspended above the soil in a moist, oxygen‑poor zone.

Image 2. Poorly drained, compacted and low-lying soils are prone to centipedegrass winter decline. Photo by Judd Lobb

Management strategies

Managing winter decline focuses on improving soil aeration, increasing rooting depth and reducing prolonged saturation. Practices that relieve compaction, such as core aeration followed by backfilling channels with a sand topdressing, help restore oxygen movement and promote aerobic decomposition of thatch. Correcting drainage issues, whether through grading, adding surface drains or improving soil structure, helps prevent water from standing through the winter months. Mowing frequently at the recommended 1.5-2 inches and avoiding scalping help reduce stress before dormancy. During the growing season, watering deeply but infrequently encourages deeper roots that are less vulnerable to winter conditions. Additionally, ensure that irrigation systems are only watering during the winter months if absolutely necessary and rainfall has not been observed for several weeks.

Summary

Warm-season turfgrass winter decline occurs when shallow rooting, prolonged saturation and reduced winter metabolism coincide with microbial activity that thrives in low‑oxygen environments. By improving drainage, reducing thatch, using topdressing wisely, managing fertility carefully and promoting deeper rooting, homeowners and turf managers can greatly reduce the likelihood of winter injury and maintain healthier turf year‑round.

P4045
4/21/26
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