Sometimes Florida yards need fertilizer to help keep them healthy, but applying too much fertilizer, too often or at the wrong time can cause water pollution.
Recent studies have shown that rising nitrate levels in many local water bodies can be traced to fertilizer. Nitrate is a form of nitrogen that is found in inorganic fertilizers. When fertilizer is needed and applied correctly, the lawn absorbs the nitrogen. However, fertilizers applied improperly can run off lawns and into local water bodies, harming water quality and threatening the plants and animals that depend on clean water for survival.
You can help protect water quality while having a beautiful lawn. Learn more with steps 1–5 or by ordering our free Do-It-Yourself Guide to Florida-Friendly Fertilizing.
Fertilizer applications vary depending on grass species, your location in the state and your desired level of lawn care. For more detailed information, visit University of Florida/IFAS.
Test Your Soil
A good approach to proper fertilization is to start with a soil test. Many Florida soils are naturally high in phosphorus, one of three major nutrients in fertilizer. If your soil test shows an adequate level of phosphorus, choose a fertilizer blend that does not contain it. Your soil test will also tell you about your soil’s pH (acidity or alkalinity) levels and other nutrient levels. You can get information on obtaining a soil test from your county Extension office or visit WaterMatters.org/yards.
Know When to Apply Fertilizer
To prevent fertilizer from washing into water bodies, it’s important to know the right time to fertilize. Follow these tips before fertilizing:
- Consider the time of year, climate, soil type and, most important, type of grass and health or condition of the lawn before applying fertilizer.
- Fertilize only when the grass is actively growing. For instance, during the winter, grass is dormant in many areas of Florida; therefore, fertilizer is not necessary. Fertilizer applied when grass is not growing wastes your money and time, since it will not be beneficially used by the grass. Instead, it will leach through the soil or run off and pollute nearby water bodies.
- If your lawn has problem areas, find out if this is related to a pest, soil or environmental problem such as excess shade or the uneven distribution of irrigation water. These problems should be corrected and not just masked by fertilization.
- If your household uses reclaimed water, check with your utility to determine if your reclaimed water has nutrients such as nitrogen and phosphorus, which are also in fertilizer. If so, you may not need to fertilize as much.
- Do not fertilize if rain is predicted in the next 24–36 hours or when a heavy rain, tropical storm, hurricane or flood is predicted.
To avoid storing leftover fertilizer, decide how much you need before you make a purchase. Don’t guess! Measure your property and calculate the total square footage of turfgrass. Do not include landscape plants in the area to be fertilized.
Read the Label
All fertilizer labels have three bold numbers. The first number on the label represents nitrogen, the second number represents phosphorus and the third number represents potassium. These are the three major nutrients your lawn needs to thrive.
In general, select a fertilizer where the first and third numbers on the label are equal or in a 2:1 ratio and the middle number is zero or as low as possible.
Look for a fertilizer where the ratio of nitrogen to phosphorus (the first to second number) is a minimum of 4 to 1. For example, a 12-3-10 and a 15-0-15 fertilizer would follow this recommendation.
Choose Slow-Release Fertilizer
Most home lawn fertilizers contain some slow-release nitrogen. It takes longer for your yard to benefit from slow-release nitrogen, but the effects will last longer. Many of these fertilizers provide fertilization for 60 days or longer, depending on environmental conditions. As a result, fewer nutrients may be wasted or lost as pollutants.
To find a slow-release fertilizer, look for these terms on the product or fertilizer tag for nitrogen:
- Timed-release, slow-release or controlled-release
- Water insoluble nitrogen
- Isobutylidene diurea (IBDU)
- Ureaform (UF)
- Sulfur-, polymer-, plastic- or resin-coated urea
Tips for Newly Planted Turf
- Do not fertilize newly planted lawns (whether seeded or sodded) until 30–60 days after planting. This ensures that there is an active root system to absorb the nutrients. Apply a complete (nitrogen, phosphorus and potassium) slow-release nitrogen fertilizer to provide 1 pound of actual nitrogen per 1,000 square feet.
- After the initial fertilization, follow UF/IFAS guidelines for your grass species for fertilizing established turf.
- Do not use weed and feed products. They may harm landscape plants if roots extend into the lawn area.
- Consider applying a soluble or chelated iron source to green the lawn without increasing growth in the summer.
- Avoid liquid and soluble nitrogen fertilizer. These products should be used only by professional turfgrass managers.
Labeling Requirements Rule
The Florida Department of Agriculture and Consumer Services passed a rule regulating labeling requirements in the state for urban turf fertilizers. The new labeling requirements will make it easier for homeowners to find lawn fertilizers with both slow-release nitrogen and low phosphorus. This rule is intended to reduce potential pollution that might result from application of excess fertilizer to lawns.
- Rule for phosphorus — application rates are not to exceed 0.25 pound per 1,000 square feet per application and are not to exceed 0.5 pound of phosphorus per 1,000 square feet per year.
- Rule for nitrogen — application rates for slow-release nitrogen are not to exceed 1 pound per 1,000 square feet per application. Application rates for quick-release nitrogen are not to exceed 0.7 pound per 1,000 square feet per application.
When applying fertilizer, the most important thing to remember is to read and follow the instructions on the fertilizer bag. Proper application will ensure maximum coverage, resulting in a healthy lawn while protecting water bodies.
Calculate Application Rates
To determine the correct amount of fertilizer per 1,000 square feet, divide 100 by the percentage of nitrogen in the bag. For example, a fertilizer with a 15-0-15 label contains 15% nitrogen, 0% phosphorus and 15% potassium. Divide 100 by 15 to get 6.6; this is the number of pounds of slow-release fertilizer needed to apply one pound of nitrogen per 1,000 square feet. This works for any fertilizer product or amount of nitrogen.
Nitrogen application rates vary according to type of turf and location in the state. For more detailed information on calculating application rates, visit University of Florida/IFAS.
Apply Using a Spreader
- Overlap your spread pattern by applying half the fertilizer in one direction and the rest in the opposite direction. This will ensure an even application and avoid the appearance of a striped lawn. Break up any clumps so that the fertilizer will not get clogged in the spreader.
- Turn off the spreader before stopping and when making turns. Then, turn it back on after you have resumed walking. Shut off the spreader when passing over pavement.
- Use a deflection shield when using a spreader near sidewalks, driveways and water bodies. This will avoid spreading fertilizer granules onto impervious surfaces or into water bodies.
- Clean spreader on the lawn, not on the sidewalk or driveway. Fertilizer granules should never be left on impervious surfaces.
Water-in your fertilizer after application with no more than ¼ inch of water. To determine how much this is, perform a catch-can test. Do this by placing empty cat food or tuna cans around the perimeter of your sprinkler or irrigation system and time how long it takes to fill them to this depth (¼ inch). Do this before fertilizing so that you know how long to run the system. This will put the nutrients at root level, where they can be taken up most efficiently. Watering-in with more water than ¼ inch can result in fertilizer leaching more rapidly through the soil.
Proper lawn maintenance is vital for the long-term health of your lawn. Appropriate mowing and watering practices must occur so your lawn will have a healthy root system, be more drought-tolerant and be able to resist pests and disease.
- Never remove more than one-third of the leaf blade at any one time. Cutting too much of the leaf blade can stress your lawn. If your lawn is under any stress (shade, traffic, drought, etc.), raise the mowing height.
- Mow at the highest height for your grass species. See chart for specific types. Mowing at lower heights can result in a shallow root system.
- Keep your mower blades sharp. A dull blade tears the grass blades, making the grass unattractive and prone to insect or disease invasion.
- Do not mow when lawn is wet. This is dangerous for you, tough on the mower and bad for the grass.
- If you miss a weekly mowing, raise the mower height so you do not remove too much of the grass blade. Bring the height back down to the recommended level gradually over the next few weeks.
- Keep grass clippings, vegetative material and vegetative debris away from storm drains, ditches, water bodies and roadways.
- Leave grass clippings on the ground. They do not contribute to thatch, and they return nutrients and organic matter back to the lawn.
- Irrigate around sunrise or in the early morning hours. You want the leaf blades to dry out fully during the day.
- Do not apply water to just wet the top of the soil; this will result in a shallow root system. Apply enough water to encourage deeper root growth.
- In most parts of Florida, irrigate to apply ½–¾ inch of water. Heavier clay soils need only about ½ inch of water while sandy soils may need up to ¾ inch of water.
Irrigation System Tips
More lawns are damaged by improper irrigation practices than by any other practice. Take control of your automatic irrigation system using these tips:
- Florida law requires that all irrigation systems have working rain sensors to override the system when enough rain has fallen. Check your rain sensor to see if it’s installed correctly and still working.
- Sprinkler heads are easily misaligned or broken, which can lead to improper water application to your lawn and may waste water as runoff. Inspect your irrigation system regularly.
- To find out how long you need to run your irrigation system, perform a catch-can test (see “Water-In Fertilizer” in Step 4). If applying these amounts causes runoff, reduce the amount of water applied. In some soils it may be necessary to first apply half the amount needed, let it percolate through the soil, and then apply the remaining water a short time later.
- Turn your system to the “off” or “manual” position. Water only when leaf blades start to fold in half lengthwise or when footprints remain visible for a few minutes. Irrigate when about 30 percent of the lawn shows these signs, unless rain is forecast in the next 24 hours.
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