Generally, nitrogen should be applied after 20 to 30 percent green-up of bermudagrass. Nitrogen applied at that time will promote leaf growth which, in turf, stimulates stolon and root development. Very early applications of soluble nitrogen increase the risk of injury from a late spring freeze. In addition to the effect of nitrogen on spring recovery, potassium has been shown to reduce winterkill and promote early spring recovery. High potassium levels in bermudagrass increase carbohydrate storage in stolons and rhizomes and reduce its susceptibility to low temperature kill and to desiccation.
Potassium also promotes root development in the fall and early spring.
In addition to the level of potassium in the grass tissue, the ratio of potassium to phosphorus in the plant can have an effect on spring recovery. Iron deficiency can also cause a delay in spring recovery in bermudagrass. Iron deficiencies are most pronounced in the early spring when soil temperatures are low. Soils with a high pH, high phosphorus level, or high moisture level are particularly prone to show iron deficiencies in the spring. Soil compaction also contributes to iron deficiencies.