Blackout Dates for Lawn Fertilizer Applications Take Effect

By Kathy Knotts  

If you have plans to fertilize your lawn next week, the Maryland Dept. of Agriculture would like to remind you that you will have to wait till spring. The Maryland Lawn Fertilizer Law, passed in 2013, means that residents and lawn-care professionals can not apply fertilizers containing phosphorus and nitrogen between Nov. 16 and Feb. 28.  

An exception exists for lawn-care professionals, who may apply up to 0.5 pound of soluble or insoluble nitrogen per 1,000 square feet to lawns they manage until December 1.  

The nutrients nitrogen and phosphorus are the key ingredients in lawn fertilizer but when it rains, those excess nutrients enter our waterways and the Chesapeake Bay. Once in the water, the fertilizer contributes to algae blooms that block sunlight from reaching our vital Bay grasses, robbing the water of oxygen and threatening the species that live there.  

Potassium and lime may still be applied during the blackout dates since they are not considered a threat to water quality. All fertilizer products are labeled with three numbers indicating the percentage of nitrogen, phosphorus, and potassium (N, P, and K).   

Citizens and lawn-care professionals may resume lawn-fertilizer applications containing nitrogen and phosphorus on March 1 as long as the ground is not frozen or heavy rain is not predicted. A soil test is required before phosphorus may be applied to established lawns.  

Fertilizer products should also not be used to melt ice and snow on steps, sidewalks, driveways, or other paved surfaces. Applying fertilizer to hard or frozen ground provides a direct pathway for nutrient runoff into storm drains that feed into the Bay.  

Maryland’s Lawn Fertilizer Law requires lawn-care professionals to be licensed and certified by the Maryland Dept. of Agriculture to apply fertilizer to the properties they manage. A list of certified professionals can be found on the department’s website. For more information about Maryland’s Lawn Fertilizer Law and fertilizer best management practices, visit: