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Feed, Water, and Mow Like a Pro 

A cross section of turfgrass in soil showing soil, roots and shoots

You can do a lot for your lawn’s beauty by fertilizing, watering, and mowing the right way. Good practices also protect ground and surface waters. Here are some of the most useful tips from turfgrass experts to care for your lawn and your water.

Contents of this page:

Feed Your Lawn Right

The right amount of nutrients at the right time can improve a poor lawn and maintain a healthy lawn better than most other actions. But one thing is never true, and that is “If one pound is good, two pounds is twice as good”. Over-fertilization causes problems for the lawn and the environment. Here are tips for feeding your lawn while protecting our bays and groundwater from contamination.

When to Fertilize your Lawn

  • Only use lawn fertilizers between April 1 and December 1.—Why? It’s actually NY State law
  • Allow grass to come out of winter dormancy before applying fertilizer. Grass only absorbs fertilizer when it is actively growing (above 55˚F).
  • Don’t waste time and money on summer fertilizers! Heat stress and drought slow grass growth and fertilizer can burn your lawn in the heat.

Fertilization Schedule for Long Island:

⇒ Mid-April to May
No more than 1 lb. slow-release nitrogen (N) per 1,000 sq. ft. (32’ x 32’).
Leave clippings on lawn to recycle nutrients and organic matter.

No more than 1 lb. slow-release nitrogen (N) per 1,000 sq. ft. (32’ x 32’).
Leave clippings on lawn to recycle nutrients and organic matter.

How to Apply Fertilizer to your Lawn

  • Feed your lawn slowly. Use controlled-release fertilizers to get more bang for your buck.
  • Sweep granules off hard surfaces and back into the lawn. Don’t let them wash away with the rain (or you’ll pollute the bays and Long Island  Sound).
  • Leave clippings on the lawn. This returns nitrogen and other nutrients to the soil.  
  • By law, New Yorkers must use zero-phosphorus fertilizers. Phosphorus is already high, too much can stunt plant growth, and the excess runs off, causing algae blooms in fresh and salt water. More information is available below.

harmful algal bloom warning sign in park

The Science of Fertilization

Lawn grasses need a variety of nutrients, water and sunlight to grow. There are primary, secondary, and micronutrients, defined by how much your lawn needs.

How do I know what my lawn needs? Let Cornell’s Lab analyze your soil nutrients to optimize conditions for growing healthy grass and saving money. 

Drawing of a bag of fertilizer with concentrations of major nutrients listed

Major plant nutrients are nitrogen (N), phosphorus (P) and potassium (K). The letters are elemental symbols and usually shortened to N-P-K, represented by the percent-by-weight of each element. 

For example, an N-P-K of 16-4-8 means:  16% nitrogen, 4% phosphorus and 8% potassium BY WEIGHT.  Therefore, in a 100-pound bag of fertilizer there would be 16 lbs of nitrate, 4 lbs of phosphate and 8 lbs of potassium. Your soil test will tell you how much of each nutrient you need.

Most fertilizers are complete, with all 3 primary nutrients. Some fertilizers may have only 1 or 2 of these nutrients, giving them a formula that looks like 16-0-8 or 36-0-0. These fertilizers will supplement nutrients and help you avoid pollution when soil analysis says a nutrient is plentiful.

Long Island lawns do not need phosphorus. Use phosphorus-free fertilizers (for example, 16-0-8 NPK) which are easy to find.

Secondary nutrients include Calcium, Magnesium and Sulfur; Micronutrients include Iron, Manganese, Zinc, Boron, Chlorine, Copper, Molybdenum and Nickel.

Slow release vs. fast release fertilizer

Long Island’s soils are very sandy, resulting in rapid percolation of rainwater into the ground, which brings surface nutrients and chemicals down into groundwater. Nitrogen is the leading cause of poor water quality in Long Island’s fresh, salt and ground waters. 

Slow, or “controlled-release" nitrogen fertilizers break down slowly, releasing small amounts of nutrients, which is good for steady plant growth and deep roots.

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Watering Your Lawn for Great Results

GA water rain gauge on a stand near a flowering gardenenerally, lawns need about one inch of water per week, which is best done in one or two applications, including rainfall. Install a simple rain gauge in your yard to measure rainfall and irrigation each week. The best time to water is from 4am to 8am. This allows the grass to dry in the morning sun, reducing the chance of turf disease.

Short, daily irrigation is unnecessary, too light and too shallow to support deep grass roots.

Pro Tip: Fine fescues are among the most drought tolerant varieties of lawn grass and will bounce back from dry spells faster than other grass types. Letting fine fescues grow taller helps preserve soil moisture.


Question: If it rains 3 inches this week and it does not rain next week, when should I water my lawn?

Answer: Water when the soil below the surface (in the root zone) has dried out. This will happen quickly in hot dry weather, but may not be an issue in cooler spring and fall. 

Pro Tip: The Northeast Regional Climate Center has a Lawn Watering Tool. Plug in your zip code and when the grass was last watered and it will tell you how much to apply that day.

Do you want to know how much rain your area has received? Check the Turf Industry ForeCast for rainfall over the last seven days. It will even tell you how long you should run your sprinkler (once you let it know how much water your sprinkler applies in an hour - instructions on how to calculate this are included).

Question: My lawn always dies in the summer heat. What should I do?

Answer: First, grasses that grow in NY will naturally go into a period of dormancy, not death, when hot dry weather sets in. The roots and crown of the plants are still alive and can remain dormant for 6 weeks without trouble.

Pro Tip: Letting your lawn go dormant is a sustainable practice that conserves water. Once rainfall returns, grass will begin to grow again. Do not fertilize a dormant lawn or you risk killing it.

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Mow Like a Pro

The principles of lawn mowing are simple.

  • Sharpen mower blades after 10 hours of mowing. Dull blades rip the grass, creating jagged edges that lose water and invite disease. (Video: How do I sharpen my mower blades?)
  • Leave the lawn clippings on the lawn! Lawn clippings contain the nutrients you just added and help create new soil. (Video: Mulch Your Clippings and Leaves)
  • Mow fallen leaves right into the lawn when fall arrives and you will greatly improve soil quality and moisture-holding capacity.
  • Mow your lawn at the highest setting to preserve plant and soil moisture and to crowd out weeds. If you mow higher, you mow less often (see below).
  • Sweep clippings off hard surfaces and back into the lawn. Don’t let them wash away with the rain (or you’ll be adding nutrients to the bays and Long Island  Sound).