Will Fertilizer Turn My Grass Brown?

Fertilizer damage can be difficult to reverse.

Too much of a good thing can damage your lawn. Most lawns thrive with a fertilizer boost, but over-fertilization can burn turfgrasses and create a brown, mottled patch instead of a green, lush expanse.

Overdose

Manufacturers produce fertilizers with specific nutrient ratios. The application directions on the fertilizer take these ratios into account, but you may accidentally spill granular fertilizer onto the lawn. Walking too slowly or overlapping causes brown streaks, especially around trees. Clean up spilled fertilizer and drench affected areas with water.

Wet Lawns

Fertilizer granules stick to wet blades and burn the foliage, creating a brown cast over large areas. Don't fertilize after watering or when dew is on the grass. If you must fertilize a wet lawn, wash the fertilizer off the blades immediately after treatment.

Other Causes

Fungal diseases, insect damage or dog urine may also cause brown areas in the lawn. Follow good lawn care practices, such as mowing high and watering deeply but infrequently, to minimize this damage. Examine brown areas for chinch bugs, underground white grubs or other pests and treat accordingly.

References

• West Virginia University Extension Service: "Tips to Help Avoid Lawn Problems"; John F. Baniecki, Ph.D.; 2000
• University of Nebraska - Lincoln: What Are These Brown Patches in My Lawn?
• University of Rhode Island Landscape Horticulture Program: General Lawn Maintenance and Renovation

Resources

• University of Minnesota Extension: "Fertilizing Lawns"; C. J. Rosen et al; 2011