Fertilize Lawns with K-8 (15-5-10)
When the grass starts greening in the spring apply nitrogen (N) at 1.5 pounds per 1000 square feet or 10 pounds of K-8 (15-5-10). Every 5 to 6 weeks following spring application, apply 7 to 9 pounds of K-8 per 1000 square feet with the last application in late fall or early winter (October-December).
Research has shown that using sulfur, iron, and zinc on a well fertilized lawn can reduce the amount of nitrogen needed to maintain green grass by 10 to 15 percent, thereby reducing the amount of vegetative growth. Reducing nitrogen levels, mowing frequency can be extended and thatch build-up reduced.
During the past decade, research has shown that top quality lawns must be fertilized with adequate levels of nitrogen and potassium. Research at North Carolina State and University of Kentucky stated that for best year round quality turf, apply fertilizer in late fall or early winter, reduced winterkill and improved turf quality in the spring. An additional benefit of this fertilizer program is earlier green-up in the spring with a denser turf.
Here are more agronomy tips on fertilizing lawns with K-8