Frost on warm season grasses

A common question we typically get this time of the year is, why does my lawn have all of these squiggly lines and discolored patches in it? This usually is caused by frost damage on Bermuda grass, Zoysia grass, or other warm season grasses. Frost is the term for several types of coatings or deposits of ice that may form in humid air in cold conditions, usually overnight. Frost forms in much of the same way as a dew on your lawn in the summer. Frost usually forms when a surface cools through loss of radiation to a temperature which is colder than the dew point of the air next to the surface. Heavy frost usually does not occur in the coldest of temperatures due to very cold air cannot hold much water vapor. Therefore, frost most often occurs when temperatures are close to 32 degrees. We refer to these striped, discolored lines as “tiger striped” frost damage since it resembles the stripes on a tiger. Our average frost date on West Tennessee lawns typically range from mid to late October. Most people refer to frost it as frost “damage”. However, frost does not cause any damage to your warm season grass but it can definitely be alarming and can appear in strange shapes and sizes. At this point in the season, your lawn is still very much alive and well and still needs food and water to survive. Even during the cold months of the year continue to water your lawn to help insulate your warm season turf as well and provide a drink of water to continue root development. A potassium based fertilizer is a form of food for your lawn and can also be applied to aid in root development. As cooler weather sets in on your Tennessee lawn, you will see it will go from its beautiful green color to brown in a matter of a few days up to a few weeks. So when you see discolored or striped areas of your warm season lawn don’t panic but continue to give it the TLC it deserves.

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