Step 7 Applying the Right Fertilizer, Correctly

Tips regarding different types and proper applications of fertilizers

Not all fertilizers are the same. For the most part, the market is dominated by synthetic fertilizers such as Scotts Fertilizer and Miracle-Gro Weed & Feed, which provide much larger nitrogen ratios than is found in organic fertilizers. (The proportion of nitrogen in the fertilizer is indicated by the first of three numbers printed on the bag that are called the N-P-K ratio, for Nitrogen-Phosphorus-Potassium). In addition to containing significantly more nitrogen, the synthetic fertilizers also provide a greater percentage of nitrogen in water-soluble form. Water-soluble nitrogen is intended to provide a quick release of the nutrient in order to get the grass green as fast as possible. Although the popular synthetic fertilizers may be generally effective at getting a quick 'green up', this forced growth is not as healthy for your grass in the long run because it can weaken the plant's cells walls, and make your turf more susceptible to insect pests. Many synthetic fertilizers are sold in combined products called 'weed and feed,' which also contain chemical pesticides that are unnecessary and can harm soil microbes, earthworms and other beneficial organisms.

Environmentally speaking, synthetic fertilizers are problematic. The significantly higher concentrations of water-soluble nitrogen are more likely to runoff or leach into ground or surface water before the turf takes it up. Adding too much nitrogen, or too much at one time, or too much nitrogen in water-soluble form, can result in nitrogen runoff into surface water or leaching into ground water. Nitrogen in waterways can lead to algae blooms and low dissolved oxygen, which harms aquatic life. Nitrogen contamination of Long Island streams, rivers, ponds, lakes, and bays is a growing concern that can result in beach closings and has recently received a great deal of media attention. Nitrogen contamination in drinking water can lead to health problems such as 'blue-baby' syndrome, and therefore requires the installation STEP 5 - Applying the Right Fertilizer, Correctlyof expensive purification equipment on private or public supply wells.

Fortunately, organic fertilizers are becoming increasingly available at Long Island stores. Organic fertilizer is slower acting than synthetics; it needs to be acted upon by microbes in the soil before it is converted into a plant-available form. This process means that organic fertilizers tend to take longer to green up, but it also means that the nitrogen remains in the soil and is fed to your grass over a longer time period. To find organic fertilizers look for the OMRI (Organic Materials Review Institute) stamp. OMRI is a nonprofit that provides "an independent review of products intended for use in certified organic production, handling and processing". You can download an extensive organic product list or verify if an existing product is certified.

In addition to choosing the correct type of fertilizer, it is important to determine if and when your lawn needs any fertilizer.

Many people think fertilization is the critical ingredient to a perfect lawn, and that more is better. The truth is some lawns will benefit from added nitrogen in the form of fertilizers, but many do not need it. Mature organically maintained lawns with sufficient organic matter and stored nitrogen in the soil often do not need any fertilizer. The first thing to remember is, if your lawn looks good to you, you don't need to add fertilizer. If your turf is thin with bare soil visible, and weeds are outcompeting the grass, then that is an indication that your lawn may need fertilization.

Low-maintenance fescues, particularly when grass clippings are left on the lawn (as we recommend in Step 2), will need very little added nitrogen. Kentucky bluegrass on the other hand, may need as much as 2-3 lbs./1,000 square feet per year. A simple approach is to apply half the year's fertilizer around Memorial Day and the other half around Labor Day. If you only fertilize once a year, Labor Day is the better time.

If your turf needs nitrogen, use organic fertilizer with slow-release water-soluble nitrogen; no more than 5% of water-soluble nitrogen is good. Most organic fertilizers seem to follow this formulation.

Do not apply more than 1 lb of nitrogen per 1,000 square feet in one application. Less than .5 lb per 1,000 sq ft is preferred. No application should be more than .25 lbs of fast-release (water soluble) nitrogen per 1,000 square feet. Low-traffic, low-maintenance lawns (organic lawns where the clippings are not collected) may need no additional nitrogen, and no more than 1 lb per 1,000 square feet a year. Very high-traffic or Kentucky bluegrass show lawns with clippings bagged, could use as much as 3-4 lbs per 1,000 square feet. Shady areas need only about half as much nitrogen as sunny areas.

The "N-P-K" ratios are listed on every bag of fertilizer. It tells you the percentage of nitrogen, phosphorus, and potassium in the product. For example, Organica Lawn Booster lists its N-P-K as: 8-1-6, which means that 8% of the total weight of the fertilizer is nitrogen. You multiply the N percentage by the total weight of the product to determine how much nitrogen you are applying. So every pound of 8-1-6 fertilizer adds .08 pounds of nitrogen. To add a half-pound of nitrogen per 1,000 square feet, you would have to apply 6.25 pounds of fertilizer (6.25 x .08 = .5) per 1,000 square feet.

Be aware of laws at the county and state level that restrict the application of nitrogen fertilizer in winter months. It is against the law to apply from November 1 to April 1 in Suffolk, November 15 and April 1 in Nassau, and from December 1 to April 1 for the rest of New York State. Fertilizer applied in cold weather, when soil temperature are below 55 degrees is a waste of money as it is more likely to run off into surface water or leach into ground water. Organic fertilizers need somewhat higher soil temperatures, because soil microbes are less active in cool soil. Additionally, do not add nitrogen fertilizer in very hot or dry conditions (the middle of summer) when grass becomes dormant, or when heavy rainfall is expected in the next 2 days, which will wash much of it away.

For more information:

Long Island Organic Landscapers
Although it's easy for the average homeowner to maintain their lawn organically, some may too busy and wish to hire a professional. In that case there are thousands of landscapers on Long Island to choose from, but only a small but growing number of experts who can maintain your lawn and landscape without the use of chemical pesticides. They can be found here.

To see all the previous steps in the series, please visit 12 Steps to an Organic Lawn 

Contact Us

Have questions about anything here? Feel free to drop us a quick note!

Of course, feel free to Contact Us.

The Sustainability Institute
7180 Republic Airport Farmingdale, New York 11735