News

Low Temperature Turf Damage

Horticulture Agent
Baker County Extension Service

During the winter months, many of us are concerned about protecting our landscape and containerized plants from cold injury. However, some of us may also notice that the lawn has received some damage as well. Injury to our warm-season turfgrass typically occurs when temperatures fall below 20°F, but can occur at temperatures in the 20s if the grass is stressed.

Dried out leaf tissue from winter winds, diseased lawns, and areas that receive heavy traffic will usually show winter injury first. Leaf blades may appear wilted or water-soaked, turning whitish brown and later turning dark brown. Other factors that tend to promote cold injury include: poor drainage due to compacted soil, excessive thatch, reduced lighting (shaded areas), excessive or late fall nitrogen fertilization, and a close mowing height. Also, a sudden cold snap without any prior frosts will do more damage than if the turf has had more time to acclimate to the colder weather.

In case you are wondering how your grass rates on cold hardiness compared to others, the following species are listed in order from the most cold-hardy species to the least cold tolerant: zoysiagrass, bermudagrass, bahiagrass, centipedegrass, seashore paspalum, carpetgrass, and St. Augustinegrass. Within these species, there are different degrees of cold tolerance between cultivars. However, the St. Augustinegrass cultivar 'Floritam' which is most commonly used throughout Florida, does not exhibit the best cold tolerance.

But regardless of which species you have, there are management practices that can easily be adopted to help minimize cold temperature damage. First, avoid planting (whether sprigged, sodded, or seeded) in fall. Spring or early summer is best because we usually receive rainfall on a more regular basis (which helps with establishment) but also gives the lawn more time to become established before the cold weather arrives. Second, avoid late fall fertilization which will promote shoot growth when the grass growth and metabolism are slowing down. This will ensure that carbohydrate reserve levels remain high, helping the grass re-grow in spring and recover from any stress it experienced during winter. Forcing new growth late in the season will also increase damage from freezing temperatures. If fall fertilization is necessary, apply it in late August or early September, and choose a fertilizer analysis such as 15-0-15. This will allow you to apply the same amount of both potassium and nitrogen. Applying potassium at a rate of ½ to 1 pound per 1000 square feet is recommended to enhance your turf's cold tolerance and promote an earlier green-up in the spring.

Mowing your lawn at the proper height throughout the year can also reduce cold damage in winter. It will allow roots to spread deeper in the soil, promoting drought tolerance and stress tolerance, and allow for greater production and storage of carbohydrates in late summer due to increased photosynthesis. Slightly taller grass will also create a warmer microclimate during winter for the dormant meristems (growing points) and the grass roots. Optimal mowing heights are as follows: Bahiagrass, 3 to 4 inches; Bermudagrass, ½ to 1 ½ inches; Centipedegrass, 1 ½ to 2 inches; St. Augustinegrass, 2 ½ to 4 inches.

If you would like more information on this subject or have other gardening questions, please contact Alicia Lamborn, Horticulture Agent, at the Baker County Extension Office by calling 259-3520 or email alamborn@ufl.edu.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating.