New Fertilizer Law

A new law, affecting lawn fertilization in Maryland, will become effective October 1, 2013. The new law will affect fertilizer manufacturers, lawn care professionals and homeowners who fertilize their own lawns. The intent of the law is to protect the Chesapeake Bay from excess nutrients entering its waters from golf courses, parks, recreation areas, athletic fields, businesses and thousands of suburban and urban lawns.

Lawn fertilizers contain many nutrients with the key ingredients being nitrogen, phosphorus, and potassium. Nitrogen (N) promotes green leafy growth, phosphorus (P) promotes root, fruit and flower development and potassium (K) promotes tolerance to disease and drought. When it rains and these nutrients are washed into the streets and then into the streams and rivers that feed the Chesapeake Bay, they fuel, or act as nutrients to
the growth of algae. The algae bloom blocks sunlight from reaching the Bay grasses which inhibits their growth. Bay grasses are important because they provide food and habitat for aquatic life, absorb and filter nutrients and pollution, and add oxygen to the water. When the algae dies it depletes the water of oxygen thereby creating “dead zones” and threatening underwater life.

The law’s implication for the homeowner is that they must follow the University of Maryland fertilizer recommendations at when applying nitrogen to lawns.

  • A single application of total nitrogen may not exceed 0.9 pound total nitrogen per 1000 square feet and 0.7 pound of water soluble nitrogen per 1000 square feet. To determine how much fertilizer to use, calculate your lawn’s square footage by multiplying the lawn’s length by width. This will help to prevent over fertilization.
  • Fertilizer should be applied only when the grass is actively growing. For seasonal and yearly fertilizer rates, visit
  • Phosphorus may only be applied to lawns when indicated by soil test results or when the homeowner is establishing, patching or renovating a lawn. Most Maryland lawns have sufficient phosphorus.
  • Homeowners must follow the label directions and only apply the application to the lawn.
  • The setback requirements state that no fertilizer application may be within 15 feet of waterways or 10 feet if a drop spreader, rotary spreader with deflector, or targeted spray liquid is used to apply fertilizer.
  • No fertilizer may be applied between November 15 and March 1 and when the ground is frozen.
  • Fertilizers may not be used as de-icers on driveways, walkways or sidewalks.
  • Do not used fertilizers when heavy rain is expected.

Here are some other hints to help fertilize your lawn responsibly:

  • Fertilize at the right time – warm season grasses in late spring or summer and cool season grasses in fall, based on soil test analysis.
  • Don’t over fertilize.
  • Apply fertilizer properly.
  • Remove no more than 1/3 of grass height each time you mow with sharpened lawn blades. This will help to conserve moisture and shade out weeds.
  • Leave grass clippings on the lawn to let them act as free, slow release fertilizer.
  • If you must water your lawn, avoid water runoff from the lawn by watering slowly, watering early in the morning using a sprinkler (in non drought conditions), and wetting to a depth of 4 to 6 inches.

Sources: University of Maryland Extension at and “Lawn Fertilizer” at

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