When and how much fertilizer do I need to apply to my warm season lawn?
Ideally, a lawn should have a soil test at least once every 5 years so that the owner can know if the pH or nutrient needs of the lawn changes. Sandy soils require more fertilizer than clay-based soils because the larger particles of the sandy soil do not hold the nutrients as well, especially nitrogen which is water soluble. When fertilizing lawns, slow release fertilizers are a better choice than quick release forms. Unless soil test results indicate otherwise, always use a balanced fertilizer such as 10-10-10, 10-20-10 or 13-13-13. These fertilizers will provide the needed nitrogen, phosphorus and potassium.
Bermuda requires 4 to 6 lbs of actual nitrogen/ 1000 sq. ft. /year. This means that if using a 10-10-10 fertilizer mix, the lawn should receive 40 to 60 lbs/ 1000 sq. ft. Two thirds of this fertilizer should be applied in one application from late April to mid-May. Bermuda grass is a heavy feeder. Although this amount of nitrogen will cause the grass to grow faster and more densely (requiring more mowing), it can actually outgrow many other weeds and grasses and choke out the undesirable plants. The last portion of the fertilizer should be applied in late June to July if water is available and the lawn is not drought stressed. If the lawn is brown at this time, do not apply fertilizer until the following spring. Applying fertilizer to a drought stressed lawn can burn the roots and damage the lawn.
If the lawn is composed of Zoysiagrass , Bahiagrass or St. Augustinegrass, apply 3 lbs of actual nitrogen/1000 sq. ft. / year. If the lawn is planted with Centipedegrass or Buffalo grass apply only 2 lbs of actual nitrogen/1000 sq. ft./year. To prevent heat stress, do not cut warm season lawns shorter than 1 ½ inches. Buffalo grass can be maintained at 3 inches.
For more information contact the OSU Extension Center, 14001 Acme Road, corner of MacArthur and Acme Road in Shawnee or 273-7683.